Differential Equations in Pumas

Author

David Widmann

1 Introduction

Pumas automatically chooses a differential equation solver that is suitable for the simulation or estimation of the dynamical system of the NLME (Nonlinear Mixed Effects) model at hand. This default solver is the preferred choice and optimized for most users and use cases. Nevertheless, in some cases the performance-accuracy trade-off can be improved by adjusting the tolerances, or possibly even the algorithm, of the differential equation solver.

In this tutorial, the Warfarin PK/PD model is used to demonstrate how to configure the differential equation solver.

2 Learning Goals

  • Observe the utility of the @vars block of a Pumas model with respect to storing dynamic variables associated with differential equations
  • Understand the main differences between common differential equation solvers for nonlinear dynamical systems
  • Learn how to adjust the algorithm and the tolerances of the differential equation solver

3 Warfarin PK/PD Model

We return to the Warfarin PK/PD model. Its dynamical system consists of three states, \(\operatorname{Depot}\), \(\operatorname{Central}\), and \(\operatorname{Turnover}\), whose dynamics are governed by the ordinary differential equations:

\[ \begin{aligned} \operatorname{Depot}'(t) &= - \operatorname{Ka} \operatorname{Depot}(t),\\ \operatorname{Central}'(t) &= \operatorname{Ka} \operatorname{Depot}(t) - \frac{\operatorname{CL}}{\operatorname{Vc}} \operatorname{Central}(t),\\ \operatorname{Turnover}'(t) &= \operatorname{rin} (1 + \operatorname{emax} \frac{\operatorname{Central}(t) / \operatorname{Vc}}{\operatorname{c50} + \operatorname{Central}(t)/\operatorname{Vc}}) - \operatorname{kout} \operatorname{Turnover}(t) \end{aligned} \]

with PK parameters \(\operatorname{Ka}\) (absorption rate), \(\operatorname{CL}\) (clearance), and \(\operatorname{Vc}\) (volume of distribution) and PD parameters \(\operatorname{rin}\), \(\operatorname{emax}\), \(\operatorname{c50}\), and \(\operatorname{kout}\).

The dynamical system can be written more concisely by introducing auxiliary variables for repeated expressions:

\[ \begin{aligned} \operatorname{Depot}'(t) &= -\operatorname{ratein}(t),\\ \operatorname{Central}'(t) &= \operatorname{ratein}(t) - \operatorname{CL} \operatorname{cp}(t),\\ \operatorname{Turnover}'(t) &= \operatorname{rin} \operatorname{pd}(t) - \operatorname{kout} \operatorname{Turnover}(t) \end{aligned} \]

with influx rate \(\operatorname{ratein}(t) := \operatorname{Ka} \operatorname{Depot}(t)\), concentration \(\operatorname{cp}(t) := \operatorname{Central}(t) / \operatorname{Vc}\), and \(\operatorname{pd}(t) := 1 + \operatorname{emax} \frac{\operatorname{cp}(t)}{\operatorname{c50} + \operatorname{cp}(t)}\).

4 Auxiliary Variables in @vars

In Pumas, dynamical systems are defined in the @dynamics block inside of the @model definition. For instance, the dynamical system of the Warfarin PK/PD model can be implemented as follows:

warfarin_pkpd_model = @model begin
    ...

    @dynamics begin
        Depot' = -Ka * Depot
        Central' = Ka * Depot - CL / Vc * Central
        Turnover' =
            rin * (1 + emax * (Central / Vc) / (cp50 + Central / Vc)) - kout * Turnover
    end

    ...
end

The same concise rewriting can be applied in a Pumas @model by defining auxiliary variables (“aliases”) in the @vars block:

warfarin_pkpd_model = @model begin
    ...

    @vars begin
        cp := Central / Vc
        ratein := Ka * Depot
        pd := 1 + emax * cp / (c50 + cp)
    end

    @dynamics begin
        Depot' = -ratein
        Central' = ratein - CL * cp
        Turnover' = rin * pd - kout * Turnover
    end

    ...
end
Tip

The walrus operator (:=) ensures that the aliases do not show up in the simulation output of the model. However, if you would like to access an alias in the simulation output, you should define the alias with =. For instance, if you want to obtain concentration cp as part of the simulation output, you can change the @vars block to

@vars begin
    cp = Central / Vc
    ratein := Ka * Depot
    pd := 1 + emax * cp / (c50 + cp)
end

5 Differential Equation Solvers

The differential equation in the Warfarin model is non-linear, as detected by Pumas (“Dynamical system type: Nonlinear ODE”):

using Pumas

warfarin_pkpd_model = @model begin
    @param begin
        # PK parameters
        """
        Clearance (L/h/70kg)
        """
        pop_CL  RealDomain(lower = 0.0, init = 0.134)
        """
        Central Volume L/70kg
        """
        pop_V  RealDomain(lower = 0.0, init = 8.11)
        """
        Absorption time (h)
        """
        pop_tabs  RealDomain(lower = 0.0, init = 0.523)
        """
        Lag time (h)
        """
        pop_lag  RealDomain(lower = 0.0, init = 0.1)
        # PD parameters
        """
        Baseline
        """
        pop_e0  RealDomain(lower = 0.0, init = 100.0)
        """
        Emax
        """
        pop_emax  RealDomain(init = -1.0)
        """
        EC50
        """
        pop_c50  RealDomain(lower = 0.0, init = 1.0)
        """
        Turnover
        """
        pop_tover  RealDomain(lower = 0.0, init = 14.0)
        # Inter-individual variability
        """
          - ΩCL
          - ΩVc
          - ΩTabs
        """
        pk_Ω  PDiagDomain([0.01, 0.01, 0.01])
        """
          - Ωe0
          - Ωemax
          - Ωec50
          - Ωturn
        """
        pd_Ω  PDiagDomain([0.01, 0.01, 0.01, 0.01])
        # Residual variability
        """
        Proportional residual error for drug concentration
        """
        σ_prop  RealDomain(lower = 0.0, init = 0.00752)
        """
        Additive residual error for drug concentration (mg/L)
        """
        σ_add  RealDomain(lower = 0.0, init = 0.0661)
        """
        Additive error for PCA
        """
        σ_fx  RealDomain(lower = 0.0, init = 0.01)
    end

    @random begin
        # mean = 0, covariance = pk_Ω
        pk_η ~ MvNormal(pk_Ω)
        # mean = 0, covariance = pd_Ω
        pd_η ~ MvNormal(pd_Ω)
    end

    @covariates FSZV FSZCL

    @pre begin
        # PK
        CL = FSZCL * pop_CL * exp(pk_η[1])
        Vc = FSZV * pop_V * exp(pk_η[2])
        tabs = pop_tabs * exp(pk_η[3])
        Ka = log(2) / tabs
        # PD
        e0 = pop_e0 * exp(pd_η[1])
        emax = pop_emax * exp(pd_η[2])
        c50 = pop_c50 * exp(pd_η[3])
        tover = pop_tover * exp(pd_η[4])
        kout = log(2) / tover
        rin = e0 * kout
        time = t
    end

    @dosecontrol begin
        lags = (Depot = pop_lag,)
    end

    @init begin
        Turnover = e0
    end

    # aliases for use in @dynamics and @derived
    @vars begin
        cp := Central / Vc
        ratein := Ka * Depot
        pd := 1 + emax * cp / (c50 + cp)
    end

    @dynamics begin
        Depot' = -ratein
        Central' = ratein - CL * cp
        Turnover' = rin * pd - kout * Turnover
    end

    @derived begin
        """
        Warfarin Concentration (mg/L)
        """
        conc ~ @. Normal(cp, sqrt((σ_prop * cp)^2 + σ_add^2))
        """
        PCA
        """
        pca ~ @. Normal(Turnover, σ_fx)
    end
end
PumasModel
  Parameters: pop_CL, pop_V, pop_tabs, pop_lag, pop_e0, pop_emax, pop_c50, pop_tover, pk_Ω, pd_Ω, σ_prop, σ_add, σ_fx
  Random effects: pk_η, pd_η
  Covariates: FSZV, FSZCL
  Dynamical system variables: Depot, Central, Turnover
  Dynamical system type: Nonlinear ODE
  Derived: conc, pca
  Observed: conc, pca

Pumas approximates the solution of the differential equation with a numerical differential equation solver. Generally, one distinguishes between solvers for stiff and non-stiff differential equations.

5.1 Stiff vs. Non-Stiff Systems

A key distinction among numerical solvers is whether they are designed for stiff or non-stiff differential equations:

  • Non-Stiff Differential Equations: These systems exhibit relatively moderate changes in their variables. Standard non-stiff solvers can efficiently approximate solutions of these systems.

  • Stiff Differential Equations: These systems contain rapidly changing components alongside more slowly varying dynamics. Non-stiff solvers typically perform poorly on stiff systems, as they may require exceedingly small step sizes to maintain numerical stability. Specialized stiff solvers are therefore employed to handle the sharp gradients and large timescale differences without compromising accuracy.

6 Pumas’s Automatic Solver Selection

By default, Pumas adopts a hybrid approach with automatic stiffness detection to switch between stiff and non-stiff solvers as needed.

6.1 Model Simulation

  • Default Solvers: Rosenbrock23 (stiff) and Tsit5 (non-stiff)
  • Tolerances: Relative tolerance \(1 \times 10^{-3}\) and absolute tolerance \(1 \times 10^{-6}\)
  • Rationale: These higher (less stringent) tolerances permit faster simulations while maintaining sufficient accuracy for exploratory and predictive modeling.

6.2 Model Fitting

  • Default Solvers: Rodas5P (stiff) and Vern7 (non-stiff)
  • Tolerances: Relative tolerance \(10^{-8}\) and absolute tolerance \(10^{-12}\)
  • Rationale: These lower (more stringent) tolerances ensure high precision during parameter estimation, which is critical for matching the model’s predictions to observed data.

The default solvers and tolerances are recommended for most users in most instances. If desired, however, it is possible to adjust these settings with the diffeq_options keyword argument.

Important

Computation time decreases as tolerances are increased. However, higher tolerances come at the cost of a less strict error control, and hence generally a less accurate solution.

6.3 Adjusting the Tolerances

The absolute and relative tolerance of the solver can be specified with abstol and reltol.

7 Absolute and Relative Tolerances

When employing a numerical solver, it is necessary to specify how accurately the solution should be computed. This precision is controlled by two key parameters:

  1. Absolute Tolerance \((\text{abstol})\)

    • Interpreted as the maximum allowable error when the solution values are near zero.
    • Ensures that numerical approximations stay within a reasonable bound, preventing physically impossible outcomes (e.g., negative concentrations) or excessive drift at small scales.
    • For instance, an absolute tolerance of \(10^{-6}\) means the solver attempts to keep the absolute error below \(10^{-6}\) whenever the solution magnitude is close to zero.
  2. Relative Tolerance \((\text{reltol})\)

    • Enforces the number of correct digits throughout the simulation, effectively controlling error relative to the current scale of the solution.
    • For example, a relative tolerance of \(10^{-3}\) implies the solver aims for three correct decimal places (i.e., the solution is accurate to within 0.1% of its current magnitude).
    • As the solution grows or shrinks, the solver adjusts its time-step size and internal computations to maintain this relative accuracy.

Sometimes decreasing tolerances can help to reduce numerical problems, e.g. to keep solutions non-negative that are mathematically guaranteed to be non-negative. Additionally, the choice of tolerances can be motivated by the application of the numerical solution: For plotting a less accurate solution, and hence larger tolerances, might be tolerable, whereas typically for model fitting a more accurate solution, and hence smaller tolerances, are beneficial.

This can be demonstrated when fitting the Warfarin model with an example dataset: Optimization fails with large tolerances of 1e-3 (relative) and 1e-6 (absolute)

fit(
    warfarin_pkpd_model,
    pop,
    init_params(warfarin_pkpd_model),
    FOCE();
    diffeq_options = (; reltol = 1e-3, abstol = 1e-6),
)
[ Info: Checking the initial parameter values.
[ Info: The initial negative log likelihood and its gradient are finite. Check passed.
Iter     Function value   Gradient norm 
     0     3.130181e+06     5.915753e+06
 * time: 0.0444488525390625
     1     5.185877e+05     8.742010e+05
 * time: 3.0191988945007324
     2     3.866957e+05     6.366584e+05
 * time: 4.067097902297974
     3     1.795019e+05     2.835377e+05
 * time: 5.092190980911255
     4     9.682619e+04     1.546512e+05
 * time: 6.1065168380737305
     5     4.791898e+04     6.820022e+04
 * time: 7.071563959121704
     6     2.907369e+04     3.509683e+04
 * time: 8.029161930084229
     7     1.827377e+04     1.713122e+04
 * time: 8.97847294807434
     8     1.260634e+04     9.563328e+03
 * time: 9.94101095199585
     9     9.403430e+03     8.611643e+03
 * time: 10.879899024963379
    10     7.325839e+03     7.634814e+03
 * time: 11.808027029037476
    11     5.926864e+03     6.625143e+03
 * time: 12.735996961593628
    12     4.942276e+03     5.562817e+03
 * time: 13.637043952941895
    13     4.139082e+03     4.326560e+03
 * time: 14.539255857467651
    14     3.563490e+03     3.065255e+03
 * time: 15.447733879089355
    15     3.296158e+03     2.170246e+03
 * time: 16.335453987121582
    16     3.216281e+03     1.669628e+03
 * time: 17.210973024368286
    17     3.205943e+03     1.487868e+03
 * time: 18.08922004699707
    18     3.204981e+03     1.444253e+03
 * time: 18.967967987060547
    19     3.204107e+03     1.417661e+03
 * time: 19.84506392478943
    20     3.201145e+03     1.361617e+03
 * time: 20.752863883972168
    21     3.194218e+03     1.282918e+03
 * time: 21.656405925750732
    22     3.175799e+03     1.158036e+03
 * time: 22.590276956558228
    23     3.130001e+03     9.774722e+02
 * time: 23.483536958694458
    24     3.016853e+03     7.265878e+02
 * time: 24.35519003868103
    25     2.749857e+03     4.107604e+02
 * time: 25.20760202407837
    26     2.137213e+03     2.318395e+02
 * time: 26.058462858200073
    27     1.756667e+03     2.281482e+02
 * time: 26.99558687210083
    28     1.380674e+03     1.613751e+02
 * time: 29.494125843048096
    29     1.328451e+03     1.298787e+02
 * time: 30.345643043518066
    30     1.287368e+03     2.435586e+02
 * time: 31.080091953277588
    31     1.263071e+03     1.616831e+02
 * time: 31.819727897644043
    32     1.254713e+03     1.796576e+02
 * time: 32.584303855895996
    33     1.247205e+03     1.996165e+02
 * time: 33.35411095619202
    34     1.243765e+03     1.938235e+02
 * time: 34.118725061416626
    35     1.240829e+03     1.739538e+02
 * time: 34.9112708568573
    36     1.240788e+03     1.744028e+02
 * time: 35.67048096656799
    37     1.240776e+03     1.743250e+02
 * time: 36.4374418258667
    38     1.240093e+03     1.687609e+02
 * time: 37.245545864105225
    39     1.239010e+03     1.586878e+02
 * time: 38.0805549621582
    40     1.236253e+03     1.305335e+02
 * time: 38.85179805755615
    41     1.232129e+03     8.229601e+01
 * time: 39.6273238658905
    42     1.228151e+03     3.735809e+01
 * time: 40.40343189239502
    43     1.226337e+03     5.238476e+01
 * time: 41.179723024368286
    44     1.226025e+03     4.868885e+01
 * time: 41.97121286392212
    45     1.226011e+03     4.583328e+01
 * time: 42.739656925201416
    46     1.226010e+03     4.536419e+01
 * time: 43.41727304458618
    47     1.226008e+03     4.466378e+01
 * time: 44.113921880722046
    48     1.226002e+03     4.336406e+01
 * time: 44.78502893447876
    49     1.225988e+03     4.102579e+01
 * time: 45.48313093185425
    50     1.225951e+03     3.656289e+01
 * time: 46.19092583656311
    51     1.225858e+03     2.865017e+01
 * time: 46.8719379901886
    52     1.225645e+03     2.863717e+01
 * time: 47.54545497894287
    53     1.225243e+03     3.015495e+01
 * time: 48.22722005844116
    54     1.224739e+03     4.057375e+01
 * time: 48.960087060928345
    55     1.224438e+03     5.072098e+01
 * time: 49.649543046951294
    56     1.224368e+03     4.561543e+01
 * time: 50.33049988746643
    57     1.224362e+03     4.124686e+01
 * time: 51.016664028167725
    58     1.224360e+03     4.008283e+01
 * time: 51.7152738571167
    59     1.224357e+03     3.807281e+01
 * time: 52.39108991622925
    60     1.224349e+03     3.507733e+01
 * time: 53.070642948150635
    61     1.224328e+03     3.152658e+01
 * time: 53.75957989692688
    62     1.224274e+03     2.940378e+01
 * time: 54.45708703994751
    63     1.224133e+03     2.814508e+01
 * time: 55.15429091453552
    64     1.223771e+03     2.816089e+01
 * time: 55.86393404006958
    65     1.222880e+03     4.493737e+01
 * time: 56.572295904159546
    66     1.220919e+03     8.628817e+01
 * time: 57.27905201911926
    67     1.217683e+03     1.137018e+02
 * time: 58.03884196281433
    68     1.214493e+03     9.066168e+01
 * time: 58.79125905036926
    69     1.212820e+03     8.381803e+01
 * time: 59.53952693939209
    70     1.212582e+03     8.589808e+01
 * time: 60.31252694129944
    71     1.212574e+03     8.557497e+01
 * time: 61.037479877471924
    72     1.212569e+03     8.522111e+01
 * time: 61.78223705291748
    73     1.212552e+03     8.416219e+01
 * time: 62.55606389045715
    74     1.212516e+03     8.236925e+01
 * time: 63.3102068901062
    75     1.212415e+03     7.841477e+01
 * time: 64.07686305046082
    76     1.212165e+03     7.017247e+01
 * time: 64.86221385002136
    77     1.211553e+03     5.231312e+01
 * time: 65.6284658908844
    78     1.210236e+03     7.254984e+01
 * time: 66.38427400588989
    79     1.208052e+03     8.652548e+01
 * time: 67.12837886810303
    80     1.205978e+03     9.811810e+01
 * time: 67.81938791275024
    81     1.205158e+03     1.085052e+02
 * time: 68.50058102607727
    82     1.205038e+03     9.706885e+01
 * time: 69.14765286445618
    83     1.205030e+03     9.297156e+01
 * time: 69.79661893844604
    84     1.205025e+03     9.142093e+01
 * time: 70.46677684783936
    85     1.205007e+03     8.794517e+01
 * time: 71.12442684173584
    86     1.204968e+03     8.329868e+01
 * time: 71.82089400291443
    87     1.204860e+03     7.519245e+01
 * time: 72.48261094093323
    88     1.204586e+03     6.676950e+01
 * time: 73.18347597122192
    89     1.203889e+03     5.914985e+01
 * time: 73.88511204719543
    90     1.202275e+03     5.659425e+01
 * time: 74.57274389266968
    91     1.199277e+03     5.457598e+01
 * time: 75.27330994606018
    92     1.195791e+03     6.434187e+01
 * time: 76.00647902488708
    93     1.193281e+03     4.404726e+01
 * time: 76.70292091369629
    94     1.192403e+03     4.696513e+01
 * time: 77.39984083175659
    95     1.192344e+03     4.826238e+01
 * time: 78.09739804267883
    96     1.192341e+03     4.836346e+01
 * time: 78.77679491043091
    97     1.192340e+03     4.843134e+01
 * time: 79.45247602462769
    98     1.192336e+03     4.854905e+01
 * time: 80.1184389591217
    99     1.192325e+03     4.873525e+01
 * time: 80.76821899414062
   100     1.192297e+03     4.901993e+01
 * time: 81.40853905677795
   101     1.192226e+03     4.941568e+01
 * time: 82.04220700263977
   102     1.192043e+03     4.985206e+01
 * time: 82.73750901222229
   103     1.191593e+03     5.001007e+01
 * time: 83.43123388290405
   104     1.190562e+03     4.892711e+01
 * time: 84.15450882911682
   105     1.188621e+03     4.482401e+01
 * time: 84.83892583847046
   106     1.186171e+03     5.565401e+01
 * time: 85.5174469947815
   107     1.184411e+03     7.195267e+01
 * time: 86.19085884094238
   108     1.183640e+03     7.480949e+01
 * time: 86.8679530620575
   109     1.183456e+03     7.309347e+01
 * time: 87.5378429889679
   110     1.183420e+03     7.276593e+01
 * time: 88.22886896133423
   111     1.183410e+03     7.363637e+01
 * time: 88.90527296066284
   112     1.183407e+03     7.448590e+01
 * time: 89.61400699615479
   113     1.183403e+03     7.577977e+01
 * time: 90.35319304466248
   114     1.183397e+03     7.712667e+01
 * time: 91.04749488830566
   115     1.183377e+03     7.953569e+01
 * time: 91.74914693832397
   116     1.183329e+03     8.300885e+01
 * time: 92.40900087356567
   117     1.183203e+03     8.805322e+01
 * time: 93.10949492454529
   118     1.182889e+03     9.423584e+01
 * time: 93.77632689476013
   119     1.182143e+03     9.919011e+01
 * time: 94.46516394615173
   120     1.180607e+03     9.577147e+01
 * time: 95.17568302154541
   121     1.178255e+03     7.337696e+01
 * time: 95.89746904373169
   122     1.176240e+03     3.404284e+01
 * time: 96.66613698005676
   123     1.175531e+03     1.922941e+01
 * time: 97.46626400947571
   124     1.175410e+03     1.933203e+01
 * time: 98.16923785209656
   125     1.175396e+03     1.964875e+01
 * time: 98.87998104095459
   126     1.175395e+03     1.966957e+01
 * time: 99.59074592590332
   127     1.175394e+03     1.960524e+01
 * time: 100.29266405105591
   128     1.175394e+03     1.957692e+01
 * time: 100.98692584037781
   129     1.175392e+03     1.945993e+01
 * time: 101.69481086730957
   130     1.175387e+03     1.938252e+01
 * time: 102.39847898483276
   131     1.175374e+03     1.915643e+01
 * time: 103.13967704772949
   132     1.175342e+03     1.892407e+01
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   133     1.175256e+03     1.840907e+01
 * time: 104.59721398353577
   134     1.175030e+03     1.936487e+01
 * time: 105.36507987976074
   135     1.174436e+03     2.656836e+01
 * time: 106.09787702560425
   136     1.172888e+03     3.906036e+01
 * time: 106.83714294433594
   137     1.169012e+03     5.824500e+01
 * time: 107.57362198829651
   138     1.160858e+03     7.724789e+01
 * time: 108.34717988967896
   139     1.151984e+03     5.979641e+01
 * time: 109.13442587852478
   140     1.150239e+03     2.132816e+02
 * time: 109.90594291687012
   141     1.147461e+03     1.267649e+02
 * time: 110.68494486808777
   142     1.143928e+03     2.373475e+01
 * time: 111.44041895866394
   143     1.142853e+03     2.225755e+01
 * time: 112.18134593963623
   144     1.141788e+03     3.914831e+01
 * time: 112.89826202392578
   145     1.141298e+03     2.253303e+01
 * time: 113.60847997665405
   146     1.140996e+03     2.098978e+01
 * time: 114.3228690624237
   147     1.140981e+03     2.094768e+01
 * time: 115.02130484580994
   148     1.140978e+03     2.098189e+01
 * time: 115.74608087539673
   149     1.140977e+03     2.101184e+01
 * time: 116.43827795982361
   150     1.140977e+03     2.100810e+01
 * time: 117.16852688789368
   151     1.140977e+03     2.097542e+01
 * time: 117.85696792602539
   152     1.140976e+03     2.094478e+01
 * time: 118.56182193756104
   153     1.140974e+03     2.089055e+01
 * time: 119.25551891326904
   154     1.140970e+03     2.083449e+01
 * time: 119.95206689834595
   155     1.140963e+03     2.076312e+01
 * time: 120.65537190437317
   156     1.140944e+03     2.068373e+01
 * time: 121.35652089118958
   157     1.140896e+03     2.060201e+01
 * time: 122.08560085296631
   158     1.140770e+03     2.053295e+01
 * time: 122.80344605445862
   159     1.140444e+03     2.051792e+01
 * time: 123.5052740573883
   160     1.139610e+03     2.178464e+01
 * time: 124.2343099117279
   161     1.138121e+03     3.276681e+01
 * time: 124.94513201713562
   162     1.135107e+03     4.596086e+01
 * time: 125.66745901107788
   163     1.132128e+03     5.673428e+01
 * time: 126.56104898452759
   164     1.130311e+03     6.297114e+01
 * time: 127.43138599395752
   165     1.126112e+03     1.303349e+02
 * time: 128.25241684913635
   166     1.116080e+03     4.102784e+01
 * time: 129.22865104675293
   167     1.114892e+03     3.653943e+01
 * time: 130.19353604316711
   168     1.112342e+03     3.437496e+01
 * time: 131.1588659286499
   169     1.111707e+03     1.636383e+01
 * time: 132.1578860282898
   170     1.111291e+03     9.909471e+00
 * time: 133.14245891571045
   171     1.111206e+03     1.001147e+01
 * time: 134.16351699829102
   172     1.111191e+03     1.040660e+01
 * time: 135.16239190101624
FittedPumasModel

Dynamical system type:               Nonlinear ODE
Solver(s): (OrdinaryDiffEqVerner.Vern7,OrdinaryDiffEqRosenbrock.Rodas5P)

Number of subjects:                             32

Observation records:         Active        Missing
    conc:                       251             47
    pca:                        232             66
    Total:                      483            113

Number of parameters:      Constant      Optimized
                                  0             18

Likelihood approximation:                     FOCE
Likelihood optimizer:                         BFGS

Termination Reason:                      NoXChange
Log-likelihood value:                   -1111.1914

-----------------------
            Estimate
-----------------------
pop_CL       0.13526
pop_V        7.9651
pop_tabs     0.61589
pop_lag      0.86532
pop_e0      96.343
pop_emax    -1.085
pop_c50      1.6306
pop_tover   14.55
pk_Ω₁,₁      0.11739
pk_Ω₂,₂      0.03428
pk_Ω₃,₃      0.24153
pd_Ω₁,₁      0.0029639
pd_Ω₂,₂      0.0022284
pd_Ω₃,₃      0.02459
pd_Ω₄,₄      0.015792
σ_prop       0.013052
σ_add        0.81408
σ_fx         3.5163
-----------------------

but fares much better with lower tolerances of 1e-8 (relative) and 1e-12 (absolute):

fit(
    warfarin_pkpd_model,
    pop,
    init_params(warfarin_pkpd_model),
    FOCE();
    diffeq_options = (; reltol = 1e-8, abstol = 1e-12),
)
[ Info: Checking the initial parameter values.
[ Info: The initial negative log likelihood and its gradient are finite. Check passed.
Iter     Function value   Gradient norm 
     0     3.125741e+06     5.911802e+06
 * time: 2.384185791015625e-5
     1     5.174461e+05     8.708698e+05
 * time: 2.234921932220459
     2     3.865265e+05     6.344302e+05
 * time: 4.1615400314331055
     3     1.804274e+05     2.829723e+05
 * time: 5.9937028884887695
     4     9.706640e+04     1.550547e+05
 * time: 7.820833921432495
     5     4.769637e+04     6.778818e+04
 * time: 9.510324954986572
     6     2.902319e+04     3.499747e+04
 * time: 11.189435005187988
     7     1.823472e+04     1.705751e+04
 * time: 12.910559892654419
     8     1.258819e+04     9.569381e+03
 * time: 14.624377965927124
     9     9.389984e+03     8.615851e+03
 * time: 16.45893883705139
    10     7.314702e+03     7.636883e+03
 * time: 18.36890983581543
    11     5.916029e+03     6.624325e+03
 * time: 20.273990869522095
    12     4.930519e+03     5.558140e+03
 * time: 22.15579581260681
    13     4.125060e+03     4.315759e+03
 * time: 24.039878845214844
    14     3.549280e+03     3.051093e+03
 * time: 25.816280841827393
    15     3.283489e+03     2.157292e+03
 * time: 27.508412837982178
    16     3.204886e+03     1.659798e+03
 * time: 29.139386892318726
    17     3.194875e+03     1.480528e+03
 * time: 30.704494953155518
    18     3.193944e+03     1.437921e+03
 * time: 32.51869487762451
    19     3.193070e+03     1.411186e+03
 * time: 34.46353888511658
    20     3.190129e+03     1.355327e+03
 * time: 36.18931198120117
    21     3.183228e+03     1.276603e+03
 * time: 37.83227181434631
    22     3.164897e+03     1.151838e+03
 * time: 39.528690814971924
    23     3.119250e+03     9.712651e+02
 * time: 41.13296699523926
    24     3.006297e+03     7.204342e+02
 * time: 42.6832389831543
    25     2.738913e+03     4.050545e+02
 * time: 44.27626395225525
    26     2.123834e+03     2.318194e+02
 * time: 45.736785888671875
    27     1.789138e+03     2.290465e+02
 * time: 47.28368592262268
    28     1.396455e+03     1.683969e+02
 * time: 51.55344295501709
    29     1.333545e+03     1.336195e+02
 * time: 53.195307970047
    30     1.297771e+03     2.452189e+02
 * time: 54.557859897613525
    31     1.266002e+03     1.523968e+02
 * time: 55.84942603111267
    32     1.255506e+03     1.733993e+02
 * time: 57.17598581314087
    33     1.247789e+03     1.971624e+02
 * time: 58.48611903190613
    34     1.244490e+03     1.915728e+02
 * time: 59.784265995025635
    35     1.240568e+03     1.704250e+02
 * time: 61.10211801528931
    36     1.240503e+03     1.711787e+02
 * time: 62.396113872528076
    37     1.240492e+03     1.711657e+02
 * time: 63.65488600730896
    38     1.239992e+03     1.687240e+02
 * time: 64.9413628578186
    39     1.239199e+03     1.624610e+02
 * time: 66.23924899101257
    40     1.236971e+03     1.400044e+02
 * time: 67.58775091171265
    41     1.233203e+03     9.442277e+01
 * time: 68.88796091079712
    42     1.228682e+03     3.273922e+01
 * time: 70.19587302207947
    43     1.226466e+03     4.997778e+01
 * time: 71.47292399406433
    44     1.226104e+03     4.904407e+01
 * time: 72.7358968257904
    45     1.226088e+03     4.675833e+01
 * time: 74.03177094459534
    46     1.226088e+03     4.628497e+01
 * time: 75.37533783912659
    47     1.226085e+03     4.541356e+01
 * time: 76.7222650051117
    48     1.226080e+03     4.402741e+01
 * time: 78.1068480014801
    49     1.226064e+03     4.142299e+01
 * time: 79.38507890701294
    50     1.226026e+03     3.663064e+01
 * time: 80.71971797943115
    51     1.225931e+03     2.851375e+01
 * time: 82.01586198806763
    52     1.225713e+03     2.844436e+01
 * time: 83.3860399723053
    53     1.225303e+03     3.026440e+01
 * time: 84.67640399932861
    54     1.224791e+03     4.157127e+01
 * time: 85.95411586761475
    55     1.224489e+03     5.047474e+01
 * time: 87.23834800720215
    56     1.224420e+03     4.451064e+01
 * time: 88.51272892951965
    57     1.224413e+03     3.994026e+01
 * time: 89.77175188064575
    58     1.224412e+03     3.879446e+01
 * time: 91.03320789337158
    59     1.224408e+03     3.677250e+01
 * time: 92.77796792984009
    60     1.224400e+03     3.377993e+01
 * time: 95.81799602508545
    61     1.224379e+03     3.158187e+01
 * time: 98.62408781051636
    62     1.224324e+03     2.925155e+01
 * time: 100.26513481140137
    63     1.224180e+03     2.815886e+01
 * time: 101.59188389778137
    64     1.223813e+03     2.818297e+01
 * time: 102.93980383872986
    65     1.222906e+03     4.598758e+01
 * time: 104.22323489189148
    66     1.220910e+03     8.692142e+01
 * time: 105.58843088150024
    67     1.217609e+03     1.136529e+02
 * time: 106.87528681755066
    68     1.214313e+03     9.030271e+01
 * time: 108.14076781272888
    69     1.212533e+03     8.868947e+01
 * time: 109.39353895187378
    70     1.212272e+03     8.970279e+01
 * time: 110.63007998466492
    71     1.212264e+03     8.921922e+01
 * time: 111.87661981582642
    72     1.212259e+03     8.882366e+01
 * time: 113.11237597465515
    73     1.212242e+03     8.761509e+01
 * time: 114.32794380187988
    74     1.212205e+03     8.561995e+01
 * time: 115.56921195983887
    75     1.212103e+03     8.125315e+01
 * time: 116.80078601837158
    76     1.211850e+03     7.229633e+01
 * time: 118.02375483512878
    77     1.211238e+03     5.321838e+01
 * time: 119.26348185539246
    78     1.209945e+03     7.377546e+01
 * time: 120.4910659790039
    79     1.207890e+03     8.404092e+01
 * time: 121.72184586524963
    80     1.206058e+03     9.148114e+01
 * time: 122.94782781600952
    81     1.205389e+03     9.689402e+01
 * time: 124.1878650188446
    82     1.205303e+03     8.594692e+01
 * time: 125.40383100509644
    83     1.205297e+03     8.262969e+01
 * time: 127.99246883392334
    84     1.205293e+03     8.096366e+01
 * time: 129.37879180908203
    85     1.205277e+03     7.747618e+01
 * time: 131.24889588356018
    86     1.205241e+03     7.259258e+01
 * time: 133.57813787460327
    87     1.205143e+03     6.664833e+01
 * time: 134.95729780197144
    88     1.204895e+03     6.374646e+01
 * time: 136.21653580665588
    89     1.204268e+03     5.753767e+01
 * time: 137.4621238708496
    90     1.202818e+03     4.866322e+01
 * time: 138.73243689537048
    91     1.200116e+03     5.085841e+01
 * time: 140.02400493621826
    92     1.196895e+03     7.139477e+01
 * time: 141.28587293624878
    93     1.194610e+03     4.693642e+01
 * time: 142.5424349308014
    94     1.193880e+03     4.874637e+01
 * time: 143.8006730079651
    95     1.193833e+03     4.997341e+01
 * time: 145.09883189201355
    96     1.193831e+03     5.008752e+01
 * time: 146.29489398002625
    97     1.193829e+03     5.014860e+01
 * time: 147.4955849647522
    98     1.193824e+03     5.025195e+01
 * time: 148.68387699127197
    99     1.193812e+03     5.040245e+01
 * time: 149.8904058933258
   100     1.193778e+03     5.061928e+01
 * time: 151.152037858963
   101     1.193693e+03     5.087910e+01
 * time: 152.38475799560547
   102     1.193472e+03     5.105104e+01
 * time: 153.66539692878723
   103     1.192926e+03     5.068579e+01
 * time: 154.980397939682
   104     1.191681e+03     4.863476e+01
 * time: 156.2937068939209
   105     1.189351e+03     4.892982e+01
 * time: 157.65465593338013
   106     1.186420e+03     7.777398e+01
 * time: 158.93764901161194
   107     1.184527e+03     8.874390e+01
 * time: 160.26991391181946
   108     1.184034e+03     8.377339e+01
 * time: 161.5546998977661
   109     1.183978e+03     7.932702e+01
 * time: 162.8830428123474
   110     1.183969e+03     7.794331e+01
 * time: 164.18269085884094
   111     1.183966e+03     7.787273e+01
 * time: 165.5228488445282
   112     1.183962e+03     7.833691e+01
 * time: 166.86115097999573
   113     1.183955e+03     7.929110e+01
 * time: 168.21114492416382
   114     1.183940e+03     8.084135e+01
 * time: 169.53141593933105
   115     1.183904e+03     8.331062e+01
 * time: 170.79682898521423
   116     1.183812e+03     8.698431e+01
 * time: 172.0329999923706
   117     1.183576e+03     9.188953e+01
 * time: 173.27450299263
   118     1.182997e+03     9.668921e+01
 * time: 174.51346802711487
   119     1.181702e+03     9.635659e+01
 * time: 175.77193880081177
   120     1.179436e+03     8.061098e+01
 * time: 177.0483798980713
   121     1.177026e+03     4.571918e+01
 * time: 178.35170602798462
   122     1.175794e+03     1.863482e+01
 * time: 179.6647388935089
   123     1.175474e+03     1.968114e+01
 * time: 181.02070784568787
   124     1.175429e+03     1.958620e+01
 * time: 182.84070301055908
   125     1.175427e+03     1.993702e+01
 * time: 185.18890500068665
   126     1.175426e+03     1.962020e+01
 * time: 187.00636887550354
   127     1.175426e+03     1.965822e+01
 * time: 188.46444988250732
   128     1.175424e+03     1.984458e+01
 * time: 189.91618490219116
   129     1.175421e+03     2.001151e+01
 * time: 191.3489909172058
   130     1.175413e+03     2.035203e+01
 * time: 192.80149698257446
   131     1.175392e+03     2.084295e+01
 * time: 194.18834495544434
   132     1.175336e+03     2.164587e+01
 * time: 195.5569658279419
   133     1.175189e+03     2.287862e+01
 * time: 196.99633502960205
   134     1.174801e+03     2.475388e+01
 * time: 198.44568300247192
   135     1.173792e+03     4.143552e+01
 * time: 199.92840385437012
   136     1.171220e+03     7.151629e+01
 * time: 201.83148980140686
   137     1.165144e+03     1.078851e+02
 * time: 203.6147379875183
   138     1.155079e+03     7.750603e+01
 * time: 205.42039895057678
   139     1.149212e+03     6.869378e+01
 * time: 207.469664812088
   140     1.146920e+03     6.357052e+01
 * time: 209.12604689598083
   141     1.144663e+03     4.948266e+01
 * time: 210.73121094703674
   142     1.143084e+03     2.539126e+01
 * time: 212.29919981956482
   143     1.141829e+03     1.979229e+01
 * time: 213.93441200256348
   144     1.141293e+03     2.050881e+01
 * time: 215.57394695281982
   145     1.141052e+03     2.076835e+01
 * time: 217.20781993865967
   146     1.140979e+03     2.090550e+01
 * time: 218.8016698360443
   147     1.140976e+03     2.094541e+01
 * time: 220.34354496002197
   148     1.140975e+03     2.099654e+01
 * time: 221.93538403511047
   149     1.140974e+03     2.099916e+01
 * time: 223.43596982955933
   150     1.140974e+03     2.099880e+01
 * time: 224.92119693756104
   151     1.140973e+03     2.099210e+01
 * time: 226.38576793670654
   152     1.140972e+03     2.098163e+01
 * time: 227.86579084396362
   153     1.140970e+03     2.096557e+01
 * time: 229.34565782546997
   154     1.140963e+03     2.094347e+01
 * time: 230.87114691734314
   155     1.140947e+03     2.091734e+01
 * time: 232.39119291305542
   156     1.140905e+03     2.089968e+01
 * time: 233.90505981445312
   157     1.140795e+03     2.093513e+01
 * time: 235.42123889923096
   158     1.140505e+03     2.116003e+01
 * time: 236.95499181747437
   159     1.139717e+03     2.228845e+01
 * time: 238.49653482437134
   160     1.137490e+03     3.499275e+01
 * time: 240.15833282470703
   161     1.132263e+03     6.112003e+01
 * time: 241.7646279335022
   162     1.129968e+03     7.040706e+01
 * time: 243.8004858493805
   163     1.128183e+03     7.684081e+01
 * time: 245.96678280830383
   164     1.125121e+03     1.651402e+02
 * time: 247.9547770023346
   165     1.124367e+03     1.524469e+02
 * time: 249.7699489593506
   166     1.117089e+03     4.431295e+01
 * time: 251.54892086982727
   167     1.113092e+03     1.609702e+01
 * time: 253.38566994667053
   168     1.111588e+03     1.011714e+01
 * time: 255.19143795967102
   169     1.111231e+03     1.280570e+01
 * time: 256.9553678035736
   170     1.111200e+03     1.186560e+01
 * time: 258.79461789131165
   171     1.111188e+03     1.091436e+01
 * time: 260.5425100326538
   172     1.111187e+03     1.052729e+01
 * time: 262.31232500076294
   173     1.111187e+03     1.067420e+01
 * time: 264.0367410182953
   174     1.111187e+03     1.055472e+01
 * time: 265.75105381011963
   175     1.111187e+03     1.036659e+01
 * time: 267.5291819572449
   176     1.111185e+03     1.017962e+01
 * time: 269.26445984840393
   177     1.111183e+03     1.017379e+01
 * time: 271.0845229625702
   178     1.111176e+03     1.016131e+01
 * time: 273.6650218963623
   179     1.111157e+03     1.013351e+01
 * time: 275.45040798187256
   180     1.111109e+03     1.006842e+01
 * time: 277.2688579559326
   181     1.110986e+03     1.142083e+01
 * time: 279.0684599876404
   182     1.110675e+03     1.751466e+01
 * time: 280.8874189853668
   183     1.109918e+03     2.591233e+01
 * time: 282.6962468624115
   184     1.108234e+03     3.515773e+01
 * time: 284.40694999694824
   185     1.105216e+03     3.902425e+01
 * time: 286.0809099674225
   186     1.101588e+03     3.080377e+01
 * time: 287.83286690711975
   187     1.098345e+03     3.607134e+01
 * time: 289.5950508117676
   188     1.094148e+03     3.626407e+01
 * time: 291.43521881103516
   189     1.093478e+03     3.314569e+01
 * time: 293.4693748950958
   190     1.092996e+03     2.938811e+01
 * time: 295.5720899105072
   191     1.092406e+03     2.138312e+01
 * time: 297.6074719429016
   192     1.092297e+03     2.975339e+01
 * time: 299.5973129272461
   193     1.091949e+03     7.639324e+00
 * time: 301.6387119293213
   194     1.091909e+03     4.276154e+00
 * time: 303.63990592956543
   195     1.091904e+03     4.346069e+00
 * time: 305.62014985084534
   196     1.091904e+03     4.337170e+00
 * time: 307.55117988586426
   197     1.091904e+03     4.342274e+00
 * time: 309.45277881622314
   198     1.091904e+03     4.344184e+00
 * time: 311.4497790336609
   199     1.091904e+03     4.346951e+00
 * time: 313.4514739513397
   200     1.091904e+03     4.349040e+00
 * time: 315.48049783706665
   201     1.091904e+03     4.348757e+00
 * time: 317.4290268421173
   202     1.091904e+03     4.343922e+00
 * time: 319.3945939540863
   203     1.091903e+03     4.333452e+00
 * time: 321.34094285964966
   204     1.091902e+03     4.317872e+00
 * time: 323.2677118778229
   205     1.091901e+03     4.295486e+00
 * time: 325.2726049423218
   206     1.091897e+03     4.261316e+00
 * time: 327.2876088619232
   207     1.091889e+03     5.125139e+00
 * time: 329.29788303375244
   208     1.091867e+03     9.013047e+00
 * time: 331.37801480293274
   209     1.091811e+03     1.513012e+01
 * time: 333.5072338581085
   210     1.091668e+03     2.427311e+01
 * time: 335.6348948478699
   211     1.091325e+03     3.642351e+01
 * time: 337.6991198062897
   212     1.090580e+03     4.801992e+01
 * time: 339.8031129837036
   213     1.089340e+03     5.062255e+01
 * time: 341.93780183792114
   214     1.088109e+03     4.437004e+01
 * time: 343.9912078380585
   215     1.087458e+03     3.115088e+01
 * time: 345.8685438632965
   216     1.087119e+03     1.183083e+01
 * time: 347.708860874176
   217     1.087046e+03     5.394070e+00
 * time: 349.56295680999756
   218     1.087043e+03     5.390830e+00
 * time: 351.4101219177246
   219     1.087043e+03     5.383737e+00
 * time: 353.2492938041687
   220     1.087043e+03     5.384236e+00
 * time: 355.1112868785858
   221     1.087043e+03     5.384636e+00
 * time: 356.91737699508667
   222     1.087043e+03     5.385864e+00
 * time: 358.7464590072632
   223     1.087043e+03     5.387179e+00
 * time: 360.56298089027405
   224     1.087042e+03     5.389948e+00
 * time: 362.38911390304565
   225     1.087041e+03     5.395184e+00
 * time: 364.2165608406067
   226     1.087039e+03     5.407029e+00
 * time: 366.05086493492126
   227     1.087033e+03     5.434556e+00
 * time: 367.8843078613281
   228     1.087016e+03     5.502571e+00
 * time: 369.7469799518585
   229     1.086972e+03     5.677167e+00
 * time: 371.5855460166931
   230     1.086849e+03     8.425733e+00
 * time: 373.43654680252075
   231     1.086459e+03     1.475408e+01
 * time: 375.27375984191895
   232     1.086446e+03     4.299557e+01
 * time: 377.01288080215454
   233     1.085092e+03     2.387717e+01
 * time: 378.8178608417511
   234     1.083538e+03     2.726422e+01
 * time: 380.5686848163605
   235     1.081685e+03     2.845459e+01
 * time: 382.3016378879547
   236     1.080396e+03     2.805425e+01
 * time: 384.1446828842163
   237     1.077803e+03     2.873905e+01
 * time: 385.8347508907318
   238     1.073139e+03     2.780340e+01
 * time: 387.5888638496399
   239     1.069921e+03     1.583445e+01
 * time: 389.39954590797424
   240     1.069621e+03     7.856085e+00
 * time: 391.18015694618225
   241     1.069531e+03     2.311783e+00
 * time: 393.02971482276917
   242     1.069509e+03     2.021453e+00
 * time: 394.86608695983887
   243     1.069491e+03     2.157500e+00
 * time: 396.5996639728546
   244     1.069488e+03     2.225422e+00
 * time: 398.35064601898193
   245     1.069488e+03     2.236782e+00
 * time: 400.08276200294495
   246     1.069488e+03     2.235390e+00
 * time: 401.8094379901886
   247     1.069488e+03     2.235490e+00
 * time: 403.5200560092926
   248     1.069488e+03     2.235491e+00
 * time: 405.4117829799652
   249     1.069488e+03     2.235259e+00
 * time: 407.25454592704773
   250     1.069488e+03     2.235150e+00
 * time: 409.0679090023041
   251     1.069488e+03     2.234587e+00
 * time: 410.8860869407654
   252     1.069487e+03     2.233171e+00
 * time: 412.7629108428955
   253     1.069486e+03     2.229015e+00
 * time: 414.6252658367157
   254     1.069484e+03     2.218016e+00
 * time: 416.4838709831238
   255     1.069477e+03     2.188614e+00
 * time: 418.36225390434265
   256     1.069460e+03     2.790832e+00
 * time: 420.23526883125305
   257     1.069418e+03     4.259790e+00
 * time: 422.1472179889679
   258     1.069326e+03     5.893844e+00
 * time: 424.0497839450836
   259     1.069168e+03     6.471844e+00
 * time: 425.9710228443146
   260     1.069008e+03     4.528747e+00
 * time: 427.8906879425049
   261     1.068940e+03     1.710450e+00
 * time: 429.79487586021423
   262     1.068930e+03     8.661473e-01
 * time: 431.690495967865
   263     1.068929e+03     8.687543e-01
 * time: 433.56481099128723
   264     1.068929e+03     8.689456e-01
 * time: 435.39104890823364
FittedPumasModel

Dynamical system type:               Nonlinear ODE
Solver(s): (OrdinaryDiffEqVerner.Vern7,OrdinaryDiffEqRosenbrock.Rodas5P)

Number of subjects:                             32

Observation records:         Active        Missing
    conc:                       251             47
    pca:                        232             66
    Total:                      483            113

Number of parameters:      Constant      Optimized
                                  0             18

Likelihood approximation:                     FOCE
Likelihood optimizer:                         BFGS

Termination Reason:                      NoXChange
Log-likelihood value:                   -1068.9294

------------------------
            Estimate
------------------------
pop_CL       0.13521
pop_V        8.0112
pop_tabs     0.56615
pop_lag      0.87614
pop_e0      96.395
pop_emax    -1.0613
pop_c50      1.4884
pop_tover   14.053
pk_Ω₁,₁      0.06929
pk_Ω₂,₂      0.020318
pk_Ω₃,₃      0.89963
pd_Ω₁,₁      0.0028776
pd_Ω₂,₂      0.00044803
pd_Ω₃,₃      0.15375
pd_Ω₄,₄      0.015014
σ_prop       0.088936
σ_add        0.41486
σ_fx         3.5814
------------------------
Tip

It is not recommended to decrease tolerances below 1e-14.

7.1 Changing the Algorithm

Usually, it should not be necessary to adjust the differential equation solver. If you change the solver, you should follow the guidelines in the SciML documentation that explains which solvers are the most efficient at the desired tolerance level.

For instance, if it is known that a differential equation is stiff, a stiff solver such as Rosenbrock23 at high tolerances or Rodas5P at low tolerances could be a possible alternative to the default auto-switching solver:

# Fitting with stiff solver Rodas5P at low tolerances (relative: 1e-8, absolute: 1e-12)
fit(
    warfarin_pkpd_model,
    pop,
    init_params(warfarin_pkpd_model),
    FOCE();
    diffeq_options = (; alg = Rodas5P(), reltol = 1e-8, abstol = 1e-12),
)
[ Info: Checking the initial parameter values.
[ Info: The initial negative log likelihood and its gradient are finite. Check passed.
Iter     Function value   Gradient norm 
     0     3.125741e+06     5.911803e+06
 * time: 1.6927719116210938e-5
     1     5.174461e+05     8.708699e+05
 * time: 9.564247131347656
     2     3.865265e+05     6.344302e+05
 * time: 17.227109909057617
     3     1.804274e+05     2.829723e+05
 * time: 25.345355987548828
     4     9.706641e+04     1.550547e+05
 * time: 34.17463707923889
     5     4.769637e+04     6.778818e+04
 * time: 41.24401807785034
     6     2.902319e+04     3.499747e+04
 * time: 48.099628925323486
     7     1.823472e+04     1.705751e+04
 * time: 55.15830993652344
     8     1.258819e+04     9.569382e+03
 * time: 62.04436898231506
     9     9.389985e+03     8.615853e+03
 * time: 68.90869998931885
    10     7.314703e+03     7.636886e+03
 * time: 75.98258805274963
    11     5.916030e+03     6.624328e+03
 * time: 83.26359510421753
    12     4.930520e+03     5.558143e+03
 * time: 90.3055169582367
    13     4.125062e+03     4.315761e+03
 * time: 96.95682096481323
    14     3.549280e+03     3.051094e+03
 * time: 103.967453956604
    15     3.283490e+03     2.157293e+03
 * time: 111.1126549243927
    16     3.204886e+03     1.659798e+03
 * time: 118.12255311012268
    17     3.194875e+03     1.480528e+03
 * time: 125.21693396568298
    18     3.193944e+03     1.437922e+03
 * time: 132.4953489303589
    19     3.193070e+03     1.411186e+03
 * time: 139.7904829978943
    20     3.190129e+03     1.355327e+03
 * time: 147.26393294334412
    21     3.183228e+03     1.276603e+03
 * time: 154.29383301734924
    22     3.164897e+03     1.151838e+03
 * time: 161.56506395339966
    23     3.119250e+03     9.712652e+02
 * time: 168.8311960697174
    24     3.006297e+03     7.204344e+02
 * time: 176.17929792404175
    25     2.738913e+03     4.050546e+02
 * time: 183.48810005187988
    26     2.123834e+03     2.318194e+02
 * time: 190.31236791610718
    27     1.789142e+03     2.290466e+02
 * time: 199.42411994934082
    28     1.396456e+03     1.683975e+02
 * time: 220.02368593215942
    29     1.333545e+03     1.336198e+02
 * time: 229.02982902526855
    30     1.297773e+03     2.452181e+02
 * time: 237.8410611152649
    31     1.266002e+03     1.523972e+02
 * time: 245.64952397346497
    32     1.255505e+03     1.734000e+02
 * time: 253.5784809589386
    33     1.247788e+03     1.971637e+02
 * time: 261.512412071228
    34     1.244490e+03     1.915744e+02
 * time: 269.08797693252563
    35     1.240568e+03     1.704280e+02
 * time: 276.64229106903076
    36     1.240502e+03     1.711813e+02
 * time: 283.97336602211
    37     1.240491e+03     1.711683e+02
 * time: 290.9710500240326
    38     1.239992e+03     1.687296e+02
 * time: 298.1024169921875
    39     1.239200e+03     1.624744e+02
 * time: 305.15316009521484
    40     1.236975e+03     1.400443e+02
 * time: 312.2441580295563
    41     1.233209e+03     9.449763e+01
 * time: 319.597275018692
    42     1.228687e+03     3.276923e+01
 * time: 326.78851795196533
    43     1.226467e+03     4.997214e+01
 * time: 333.74038910865784
    44     1.226104e+03     4.905105e+01
 * time: 340.7573299407959
    45     1.226088e+03     4.676122e+01
 * time: 347.6935420036316
    46     1.226087e+03     4.628674e+01
 * time: 354.536376953125
    47     1.226085e+03     4.541753e+01
 * time: 361.41191697120667
    48     1.226080e+03     4.403288e+01
 * time: 368.18379306793213
    49     1.226064e+03     4.143315e+01
 * time: 374.916463136673
    50     1.226026e+03     3.664876e+01
 * time: 382.5936470031738
    51     1.225931e+03     2.851383e+01
 * time: 389.60882592201233
    52     1.225714e+03     2.844460e+01
 * time: 396.3549530506134
    53     1.225304e+03     3.025732e+01
 * time: 403.13479709625244
    54     1.224793e+03     4.151448e+01
 * time: 409.96794295310974
    55     1.224489e+03     5.047755e+01
 * time: 416.54454803466797
    56     1.224420e+03     4.452753e+01
 * time: 423.30796003341675
    57     1.224413e+03     3.994380e+01
 * time: 429.9929530620575
    58     1.224412e+03     3.879465e+01
 * time: 436.99037194252014
    59     1.224408e+03     3.677922e+01
 * time: 443.7821590900421
    60     1.224400e+03     3.379126e+01
 * time: 450.470477104187
    61     1.224379e+03     3.158821e+01
 * time: 457.0885920524597
    62     1.224324e+03     2.926306e+01
 * time: 463.8231029510498
    63     1.224181e+03     2.815869e+01
 * time: 470.557902097702
    64     1.223815e+03     2.818300e+01
 * time: 477.3216440677643
    65     1.222911e+03     4.583041e+01
 * time: 484.0668399333954
    66     1.220921e+03     8.675281e+01
 * time: 490.8283860683441
    67     1.217625e+03     1.136294e+02
 * time: 497.7941861152649
    68     1.214324e+03     9.050244e+01
 * time: 504.77468395233154
    69     1.212536e+03     8.867180e+01
 * time: 511.6411371231079
    70     1.212272e+03     8.970655e+01
 * time: 518.4601669311523
    71     1.212263e+03     8.922293e+01
 * time: 525.782112121582
    72     1.212259e+03     8.882951e+01
 * time: 532.7552311420441
    73     1.212242e+03     8.761908e+01
 * time: 539.622740983963
    74     1.212205e+03     8.562573e+01
 * time: 546.4403150081635
    75     1.212102e+03     8.125881e+01
 * time: 553.223384141922
    76     1.211850e+03     7.230599e+01
 * time: 559.7855930328369
    77     1.211238e+03     5.323492e+01
 * time: 566.4570059776306
    78     1.209946e+03     7.373618e+01
 * time: 572.8393499851227
    79     1.207891e+03     8.401772e+01
 * time: 579.4438970088959
    80     1.206059e+03     9.146801e+01
 * time: 586.1869020462036
    81     1.205389e+03     9.690592e+01
 * time: 592.9429619312286
    82     1.205302e+03     8.595286e+01
 * time: 599.6726109981537
    83     1.205296e+03     8.263040e+01
 * time: 606.5938370227814
    84     1.205292e+03     8.096547e+01
 * time: 613.7157459259033
    85     1.205276e+03     7.747632e+01
 * time: 620.398411989212
    86     1.205240e+03     7.259211e+01
 * time: 627.3925409317017
    87     1.205143e+03     6.664635e+01
 * time: 634.3302760124207
    88     1.204894e+03     6.374389e+01
 * time: 641.1192979812622
    89     1.204267e+03     5.753484e+01
 * time: 647.9874129295349
    90     1.202818e+03     4.869938e+01
 * time: 654.5895130634308
    91     1.200117e+03     5.087313e+01
 * time: 660.8868651390076
    92     1.196896e+03     7.141162e+01
 * time: 667.2440299987793
    93     1.194612e+03     4.695316e+01
 * time: 673.7502119541168
    94     1.193881e+03     4.874366e+01
 * time: 679.8972790241241
    95     1.193834e+03     4.997038e+01
 * time: 686.088268995285
    96     1.193832e+03     5.008442e+01
 * time: 692.1031010150909
    97     1.193830e+03     5.014549e+01
 * time: 698.178906917572
    98     1.193825e+03     5.024884e+01
 * time: 704.2186529636383
    99     1.193813e+03     5.039938e+01
 * time: 710.3019299507141
   100     1.193779e+03     5.061632e+01
 * time: 716.7501790523529
   101     1.193694e+03     5.087641e+01
 * time: 723.5223860740662
   102     1.193473e+03     5.104895e+01
 * time: 729.612270116806
   103     1.192927e+03     5.068500e+01
 * time: 735.7495429515839
   104     1.191682e+03     4.863684e+01
 * time: 741.8964419364929
   105     1.189353e+03     4.890365e+01
 * time: 748.0847179889679
   106     1.186424e+03     7.778082e+01
 * time: 754.2442560195923
   107     1.184533e+03     8.873607e+01
 * time: 760.4056119918823
   108     1.184042e+03     8.376145e+01
 * time: 766.8266670703888
   109     1.183986e+03     7.931813e+01
 * time: 774.3262801170349
   110     1.183978e+03     7.793645e+01
 * time: 781.0351390838623
   111     1.183974e+03     7.786675e+01
 * time: 787.6291790008545
   112     1.183970e+03     7.833168e+01
 * time: 794.148992061615
   113     1.183963e+03     7.928653e+01
 * time: 800.490788936615
   114     1.183949e+03     8.083870e+01
 * time: 806.875657081604
   115     1.183913e+03     8.331100e+01
 * time: 813.2905900478363
   116     1.183820e+03     8.698958e+01
 * time: 819.7315990924835
   117     1.183584e+03     9.190093e+01
 * time: 826.1487169265747
   118     1.183003e+03     9.670514e+01
 * time: 832.6487619876862
   119     1.181706e+03     9.636548e+01
 * time: 839.0561239719391
   120     1.179435e+03     8.059042e+01
 * time: 845.3655459880829
   121     1.177024e+03     4.567337e+01
 * time: 851.7256000041962
   122     1.175793e+03     1.863452e+01
 * time: 858.1589479446411
   123     1.175474e+03     1.967979e+01
 * time: 864.3829779624939
   124     1.175430e+03     1.958939e+01
 * time: 870.673730134964
   125     1.175427e+03     1.993415e+01
 * time: 876.8294229507446
   126     1.175427e+03     1.962015e+01
 * time: 883.2819080352783
   127     1.175426e+03     1.965822e+01
 * time: 890.2989299297333
   128     1.175424e+03     1.984190e+01
 * time: 896.939444065094
   129     1.175422e+03     2.000843e+01
 * time: 903.6549799442291
   130     1.175413e+03     2.034664e+01
 * time: 910.2151279449463
   131     1.175392e+03     2.083524e+01
 * time: 916.7032480239868
   132     1.175336e+03     2.163395e+01
 * time: 923.1635639667511
   133     1.175190e+03     2.286075e+01
 * time: 929.634603023529
   134     1.174803e+03     2.472708e+01
 * time: 936.2510330677032
   135     1.173797e+03     4.124367e+01
 * time: 942.8426921367645
   136     1.171232e+03     7.123154e+01
 * time: 949.5383780002594
   137     1.165167e+03     1.075848e+02
 * time: 957.3163070678711
   138     1.155096e+03     7.751300e+01
 * time: 964.7580709457397
   139     1.149210e+03     6.815707e+01
 * time: 972.0830600261688
   140     1.146904e+03     6.218499e+01
 * time: 979.3557410240173
   141     1.144688e+03     5.158716e+01
 * time: 986.6182990074158
   142     1.143100e+03     2.555104e+01
 * time: 993.6984441280365
   143     1.141816e+03     1.970245e+01
 * time: 1000.8065099716187
   144     1.141294e+03     2.048648e+01
 * time: 1007.906336069107
   145     1.141044e+03     2.076701e+01
 * time: 1014.9837980270386
   146     1.140979e+03     2.090339e+01
 * time: 1022.0832829475403
   147     1.140976e+03     2.094515e+01
 * time: 1029.0339241027832
   148     1.140975e+03     2.099576e+01
 * time: 1036.0739920139313
   149     1.140974e+03     2.099888e+01
 * time: 1043.1141419410706
   150     1.140974e+03     2.099931e+01
 * time: 1050.135108947754
   151     1.140973e+03     2.099295e+01
 * time: 1057.1122570037842
   152     1.140972e+03     2.098305e+01
 * time: 1064.1448090076447
   153     1.140970e+03     2.096756e+01
 * time: 1071.2270259857178
   154     1.140963e+03     2.094619e+01
 * time: 1079.986871957779
   155     1.140947e+03     2.092087e+01
 * time: 1089.2260010242462
   156     1.140906e+03     2.090400e+01
 * time: 1096.2722990512848
   157     1.140797e+03     2.093964e+01
 * time: 1106.8431010246277
   158     1.140511e+03     2.116231e+01
 * time: 1115.0258779525757
   159     1.139732e+03     2.193009e+01
 * time: 1121.851938009262
   160     1.137531e+03     3.209812e+01
 * time: 1128.6939299106598
   161     1.132353e+03     5.451900e+01
 * time: 1135.6939430236816
   162     1.130098e+03     6.354058e+01
 * time: 1143.1910309791565
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
   163     1.128599e+03     6.862520e+01
 * time: 1150.8915359973907
   164     1.127623e+03     8.385757e+01
 * time: 1158.3381469249725
   165     1.122228e+03     1.204824e+02
 * time: 1165.3083460330963
   166     1.118774e+03     1.225695e+02
 * time: 1172.1833729743958
   167     1.115679e+03     4.611268e+01
 * time: 1178.971202135086
   168     1.113979e+03     3.434831e+01
 * time: 1185.7568929195404
   169     1.112521e+03     3.523199e+01
 * time: 1192.562714099884
   170     1.111267e+03     1.228403e+01
 * time: 1199.4687149524689
   171     1.111189e+03     1.078353e+01
 * time: 1206.3638129234314
   172     1.111187e+03     1.048242e+01
 * time: 1213.0903940200806
   173     1.111187e+03     1.070654e+01
 * time: 1219.8539700508118
   174     1.111187e+03     1.057812e+01
 * time: 1226.4931271076202
   175     1.111187e+03     1.055136e+01
 * time: 1233.2575120925903
   176     1.111186e+03     1.049712e+01
 * time: 1241.0216619968414
   177     1.111185e+03     1.042508e+01
 * time: 1247.8158819675446
   178     1.111181e+03     1.030463e+01
 * time: 1254.5020790100098
   179     1.111173e+03     1.018028e+01
 * time: 1261.5860290527344
   180     1.111150e+03     1.017084e+01
 * time: 1268.9996869564056
   181     1.111091e+03     1.547976e+01
 * time: 1276.3248529434204
   182     1.110938e+03     2.528645e+01
 * time: 1283.7103209495544
   183     1.110546e+03     4.010028e+01
 * time: 1291.0377659797668
   184     1.109576e+03     6.035708e+01
 * time: 1298.412682056427
   185     1.107416e+03     8.168777e+01
 * time: 1305.7562301158905
   186     1.103899e+03     9.586365e+01
 * time: 1313.0045490264893
   187     1.100518e+03     1.082019e+02
 * time: 1320.2475769519806
   188     1.096703e+03     1.051881e+02
 * time: 1327.4893231391907
   189     1.092614e+03     3.371950e+01
 * time: 1334.9684300422668
   190     1.092108e+03     2.854225e+01
 * time: 1342.3084149360657
   191     1.091924e+03     8.267155e+00
 * time: 1349.379548072815
   192     1.091910e+03     4.388021e+00
 * time: 1359.1478741168976
   193     1.091908e+03     4.381246e+00
 * time: 1366.608146905899
   194     1.091906e+03     4.351855e+00
 * time: 1374.6234240531921
   195     1.091905e+03     4.347981e+00
 * time: 1382.7338030338287
   196     1.091904e+03     4.344942e+00
 * time: 1391.199077129364
   197     1.091904e+03     4.343567e+00
 * time: 1398.7811980247498
   198     1.091904e+03     4.341811e+00
 * time: 1407.1851029396057
   199     1.091904e+03     4.338160e+00
 * time: 1414.9101159572601
   200     1.091904e+03     4.331286e+00
 * time: 1423.3089709281921
   201     1.091904e+03     4.319913e+00
 * time: 1431.365534067154
   202     1.091903e+03     4.299872e+00
 * time: 1439.0423829555511
   203     1.091901e+03     4.267805e+00
 * time: 1446.0664689540863
   204     1.091897e+03     4.211166e+00
 * time: 1452.9909870624542
   205     1.091886e+03     4.118011e+00
 * time: 1461.526076078415
   206     1.091856e+03     4.884541e+00
 * time: 1469.0294330120087
   207     1.091780e+03     7.435767e+00
 * time: 1476.3803629875183
   208     1.091587e+03     1.171416e+01
 * time: 1484.5305740833282
   209     1.091126e+03     1.720748e+01
 * time: 1492.0590479373932
   210     1.090066e+03     2.180540e+01
 * time: 1499.547033071518
   211     1.088566e+03     2.176055e+01
 * time: 1506.8953120708466
   212     1.087529e+03     2.216379e+01
 * time: 1514.4804999828339
   213     1.087131e+03     6.871069e+00
 * time: 1521.8601710796356
   214     1.087053e+03     5.487618e+00
 * time: 1529.0764410495758
   215     1.087044e+03     5.346767e+00
 * time: 1536.4355199337006
   216     1.087043e+03     5.364351e+00
 * time: 1543.4889059066772
   217     1.087043e+03     5.380873e+00
 * time: 1550.9210081100464
   218     1.087043e+03     5.385017e+00
 * time: 1557.981153011322
   219     1.087043e+03     5.387076e+00
 * time: 1565.2259891033173
   220     1.087043e+03     5.393037e+00
 * time: 1572.5008299350739
   221     1.087043e+03     5.401737e+00
 * time: 1579.8430199623108
   222     1.087042e+03     5.417220e+00
 * time: 1587.0042719841003
   223     1.087041e+03     5.443370e+00
 * time: 1594.2000019550323
   224     1.087039e+03     5.489836e+00
 * time: 1601.4302699565887
   225     1.087032e+03     5.575602e+00
 * time: 1609.1601889133453
   226     1.087015e+03     5.744360e+00
 * time: 1616.7147190570831
   227     1.086967e+03     8.458307e+00
 * time: 1624.278650045395
   228     1.086833e+03     1.434823e+01
 * time: 1631.8946211338043
   229     1.086295e+03     2.779692e+01
 * time: 1639.6357259750366
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: First function call produced NaNs. Exiting. Double check that none of the initial conditions, parameters, or timespan values are NaN.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/initdt.jl:253
Warning: Automatic dt set the starting dt as NaN, causing instability. Exiting.
@ OrdinaryDiffEqCore ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/OrdinaryDiffEqCore/LG1u6/src/solve.jl:654
Warning: NaN dt detected. Likely a NaN value in the state, parameters, or derivative value caused this outcome.
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:583
Warning: At t=0.4500886809099674, dt was forced below floating point epsilon 5.551115123125783e-17, and step error estimate = 4.8708450078891075e20. Aborting. There is either an error in your model specification or the true solution is unstable (or the true solution can not be represented in the precision of ForwardDiff.Dual{ForwardDiff.Tag{Pumas.Tag, Float64}, Float64, 7}).
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:623
Warning: At t=0.4500886809099674, dt was forced below floating point epsilon 5.551115123125783e-17, and step error estimate = 4.8708450078891075e20. Aborting. There is either an error in your model specification or the true solution is unstable (or the true solution can not be represented in the precision of ForwardDiff.Dual{ForwardDiff.Tag{Pumas.Tag, Float64}, Float64, 7}).
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:623
   230     1.086121e+03     6.179899e+01
 * time: 1650.7464311122894
   231     1.085699e+03     4.269436e+01
 * time: 1660.8280310630798
   232     1.085153e+03     5.101086e+01
 * time: 1676.3455090522766
   233     1.084625e+03     5.803468e+01
 * time: 1687.4738569259644
   234     1.084371e+03     6.244198e+01
 * time: 1699.0825290679932
   235     1.083958e+03     6.785742e+01
 * time: 1710.8908619880676
   236     1.083163e+03     6.963805e+01
 * time: 1720.6300101280212
   237     1.081667e+03     6.332470e+01
 * time: 1731.2140791416168
   238     1.080941e+03     5.916175e+01
 * time: 1750.4753930568695
   239     1.079241e+03     5.431208e+01
 * time: 1761.100774049759
   240     1.076096e+03     3.465388e+01
 * time: 1771.687518119812
   241     1.072649e+03     1.670281e+01
 * time: 1780.8012299537659
   242     1.069992e+03     1.935661e+01
 * time: 1788.6073529720306
   243     1.069558e+03     3.678375e+00
 * time: 1796.4083559513092
   244     1.069496e+03     2.270102e+00
 * time: 1804.2123279571533
   245     1.069488e+03     2.221349e+00
 * time: 1811.8281841278076
   246     1.069488e+03     2.237998e+00
 * time: 1820.3182721138
   247     1.069488e+03     2.236062e+00
 * time: 1827.980148077011
   248     1.069488e+03     2.235507e+00
 * time: 1835.7463490962982
   249     1.069488e+03     2.234690e+00
 * time: 1843.6164569854736
   250     1.069488e+03     2.233625e+00
 * time: 1851.464313030243
   251     1.069488e+03     2.231719e+00
 * time: 1859.7571630477905
   252     1.069488e+03     2.228573e+00
 * time: 1867.4882979393005
   253     1.069487e+03     2.223013e+00
 * time: 1875.2372579574585
   254     1.069487e+03     2.212970e+00
 * time: 1885.185487985611
   255     1.069485e+03     2.193875e+00
 * time: 1892.7460520267487
   256     1.069481e+03     2.558103e+00
 * time: 1900.3854820728302
   257     1.069470e+03     4.099866e+00
 * time: 1909.4473600387573
   258     1.069441e+03     6.445399e+00
 * time: 1917.183618068695
   259     1.069374e+03     9.551161e+00
 * time: 1925.2555899620056
   260     1.069241e+03     1.204286e+01
 * time: 1935.4242289066315
   261     1.069065e+03     1.050115e+01
 * time: 1943.2474761009216
   262     1.068958e+03     5.184001e+00
 * time: 1950.9922270774841
   263     1.068932e+03     1.288840e+00
 * time: 1958.7259039878845
   264     1.068929e+03     8.682448e-01
 * time: 1966.2240579128265
   265     1.068929e+03     8.688495e-01
 * time: 1973.8010659217834
   266     1.068929e+03     8.688500e-01
 * time: 1981.6565670967102
   267     1.068929e+03     8.689152e-01
 * time: 1989.2063081264496
   268     1.068929e+03     8.689157e-01
 * time: 1996.95889210701
   269     1.068929e+03     8.690133e-01
 * time: 2004.4847071170807
   270     1.068929e+03     8.690133e-01
 * time: 2013.5737841129303
   271     1.068929e+03     8.693257e-01
 * time: 2022.082277059555
   272     1.068929e+03     8.693100e-01
 * time: 2029.2785460948944
   273     1.068919e+03     9.277276e-01
 * time: 2037.3966550827026
   274     1.068907e+03     1.626480e+00
 * time: 2046.6672599315643
   275     1.068835e+03     4.106347e+00
 * time: 2057.245882987976
   276     1.068726e+03     6.157731e+00
 * time: 2068.4691281318665
   277     1.068548e+03     7.201969e+00
 * time: 2080.8171451091766
   278     1.068415e+03     5.646200e+00
 * time: 2091.022810935974
   279     1.068386e+03     3.803550e+00
 * time: 2100.4798350334167
   280     1.068384e+03     3.184721e+00
 * time: 2112.120849132538
   281     1.068384e+03     2.938192e+00
 * time: 2123.9794409275055
   282     1.068384e+03     2.942962e+00
 * time: 2137.305746078491
   283     1.068384e+03     2.943184e+00
 * time: 2148.965430021286
   284     1.068384e+03     2.943716e+00
 * time: 2164.621393918991
   285     1.068384e+03     2.944531e+00
 * time: 2179.9104170799255
   286     1.068384e+03     2.944646e+00
 * time: 2198.838725090027
   287     1.068384e+03     2.944770e+00
 * time: 2211.9734830856323
   288     1.068384e+03     2.944962e+00
 * time: 2227.798793077469
   289     1.068384e+03     2.944984e+00
 * time: 2240.173574924469
   290     1.068384e+03     2.945026e+00
 * time: 2252.1921689510345
   291     1.068384e+03     2.945033e+00
 * time: 2264.480735063553
   292     1.068384e+03     2.945039e+00
 * time: 2278.1172411441803
   293     1.068384e+03     2.945044e+00
 * time: 2293.1370990276337
   294     1.068384e+03     2.945044e+00
 * time: 2304.5833909511566
   295     1.068384e+03     2.945044e+00
 * time: 2316.9158329963684
   296     1.068384e+03     2.945044e+00
 * time: 2328.5985469818115
   297     1.068384e+03     2.945044e+00
 * time: 2337.980791091919
   298     1.068384e+03     2.945044e+00
 * time: 2346.998826980591
   299     1.068384e+03     2.945044e+00
 * time: 2356.8434779644012
   300     1.068384e+03     2.945044e+00
 * time: 2366.515361070633
   301     1.068384e+03     2.945044e+00
 * time: 2376.1823360919952
   302     1.068384e+03     2.945044e+00
 * time: 2385.078877925873
   303     1.068384e+03     2.945044e+00
 * time: 2394.3149909973145
   304     1.068384e+03     2.945044e+00
 * time: 2409.1285910606384
   305     1.068384e+03     3.074478e+00
 * time: 2418.3943049907684
   306     1.068384e+03     3.057700e+00
 * time: 2426.3685591220856
   307     1.068384e+03     3.030813e+00
 * time: 2434.2940471172333
   308     1.068384e+03     3.005745e+00
 * time: 2442.023374080658
   309     1.068384e+03     2.974044e+00
 * time: 2450.4006791114807
   310     1.068384e+03     2.945854e+00
 * time: 2460.219269990921
   311     1.068383e+03     2.905870e+00
 * time: 2469.0537810325623
   312     1.068382e+03     2.819225e+00
 * time: 2484.123179912567
   313     1.068381e+03     2.581914e+00
 * time: 2495.0115010738373
   314     1.068376e+03     1.940126e+00
 * time: 2502.665009021759
   315     1.068367e+03     1.682057e+00
 * time: 2510.273323059082
   316     1.068350e+03     2.787006e+00
 * time: 2517.8747720718384
   317     1.068331e+03     6.870737e+00
 * time: 2525.4204199314117
   318     1.068322e+03     9.136899e+00
 * time: 2532.6881170272827
   319     1.068319e+03     9.093888e+00
 * time: 2541.096415042877
   320     1.068318e+03     8.702840e+00
 * time: 2548.1413190364838
   321     1.068317e+03     8.067498e+00
 * time: 2555.060490131378
   322     1.068313e+03     7.024566e+00
 * time: 2562.017143011093
   323     1.068305e+03     5.566463e+00
 * time: 2568.9350731372833
   324     1.068294e+03     4.311204e+00
 * time: 2576.0539610385895
   325     1.068285e+03     4.366941e+00
 * time: 2583.1316571235657
   326     1.068282e+03     5.297662e+00
 * time: 2590.9156980514526
   327     1.068282e+03     5.794863e+00
 * time: 2600.8535120487213
   328     1.068282e+03     5.858759e+00
 * time: 2608.492994070053
   329     1.068282e+03     5.858759e+00
 * time: 2617.479418992996
   330     1.068282e+03     5.890965e+00
 * time: 2624.998419046402
   331     1.068282e+03     5.889642e+00
 * time: 2632.6605911254883
   332     1.068282e+03     5.755927e+00
 * time: 2640.347897052765
   333     1.068282e+03     5.654191e+00
 * time: 2648.6581149101257
   334     1.068281e+03     5.457610e+00
 * time: 2655.9265460968018
   335     1.068280e+03     5.325147e+00
 * time: 2663.280911922455
   336     1.068280e+03     5.359845e+00
 * time: 2672.979134082794
   337     1.068279e+03     5.558458e+00
 * time: 2680.3815290927887
   338     1.068278e+03     5.765445e+00
 * time: 2687.827162027359
   339     1.068278e+03     5.998734e+00
 * time: 2695.183377981186
   340     1.068276e+03     6.340911e+00
 * time: 2702.45348405838
   341     1.068272e+03     6.826786e+00
 * time: 2709.8414130210876
   342     1.068262e+03     7.444708e+00
 * time: 2717.178615093231
   343     1.068237e+03     7.966869e+00
 * time: 2724.5161480903625
   344     1.068187e+03     7.662772e+00
 * time: 2732.061765909195
   345     1.068105e+03     5.453572e+00
 * time: 2740.41206908226
   346     1.068030e+03     2.116637e+00
 * time: 2747.8398559093475
   347     1.068004e+03     2.672269e-01
 * time: 2755.5182321071625
   348     1.068001e+03     4.076140e-01
 * time: 2763.127718925476
   349     1.067999e+03     5.992600e-01
 * time: 2770.8160939216614
   350     1.067997e+03     5.810130e-01
 * time: 2778.35297703743
   351     1.067994e+03     3.112045e-01
 * time: 2786.5953829288483
   352     1.067992e+03     7.689723e-02
 * time: 2796.2118039131165
   353     1.067992e+03     9.091969e-02
 * time: 2806.3966660499573
   354     1.067992e+03     9.785125e-02
 * time: 2818.222280025482
   355     1.067992e+03     1.024830e-01
 * time: 2829.2268121242523
   356     1.067992e+03     1.051058e-01
 * time: 2839.9516320228577
   357     1.067992e+03     1.057116e-01
 * time: 2848.9413590431213
   358     1.067992e+03     1.057207e-01
 * time: 2858.4513239860535
   359     1.067992e+03     1.057207e-01
 * time: 2872.8086800575256
   360     1.067992e+03     1.057044e-01
 * time: 2888.176573038101
   361     1.067992e+03     1.056554e-01
 * time: 2899.0949490070343
   362     1.067992e+03     1.056554e-01
 * time: 2910.5532641410828
   363     1.067992e+03     1.052666e-01
 * time: 2923.9838371276855
   364     1.067992e+03     1.052895e-01
 * time: 2940.477483034134
   365     1.067992e+03     1.052895e-01
 * time: 2959.7988369464874
   366     1.067992e+03     1.052895e-01
 * time: 2977.7432510852814
FittedPumasModel

Dynamical system type:               Nonlinear ODE
Solver(s):        OrdinaryDiffEqRosenbrock.Rodas5P

Number of subjects:                             32

Observation records:         Active        Missing
    conc:                       251             47
    pca:                        232             66
    Total:                      483            113

Number of parameters:      Constant      Optimized
                                  0             18

Likelihood approximation:                     FOCE
Likelihood optimizer:                         BFGS

Termination Reason:              NoObjectiveChange
Log-likelihood value:                   -1067.9916

-----------------------
            Estimate
-----------------------
pop_CL       0.13521
pop_V        8.0132
pop_tabs     0.57101
pop_lag      0.87564
pop_e0      96.399
pop_emax    -1.0615
pop_c50      1.4912
pop_tover   14.05
pk_Ω₁,₁      0.068018
pk_Ω₂,₂      0.02105
pk_Ω₃,₃      0.86339
pd_Ω₁,₁      0.0029815
pd_Ω₂,₂      2.3946e-7
pd_Ω₃,₃      0.14556
pd_Ω₄,₄      0.015351
σ_prop       0.088484
σ_add        0.41684
σ_fx         3.5802
-----------------------

On the other hand, if it is known that a differential equation is non-stiff (this might be difficult to guarantee for all admissible parameter values), a non-stiff solver such as Tsit5 at high tolerances or Vern7 at low tolerances could be an alternative to the default solver:

# Fitting with the non-stiff solver Vern7 at low tolerances (relative: 1e-8, absolute: 1e-12)
fit(
    warfarin_pkpd_model,
    pop,
    init_params(warfarin_pkpd_model),
    FOCE();
    diffeq_options = (; alg = Vern7(), reltol = 1e-8, abstol = 1e-12),
)
[ Info: Checking the initial parameter values.
[ Info: The initial negative log likelihood and its gradient are finite. Check passed.
Iter     Function value   Gradient norm 
     0     3.125741e+06     5.911802e+06
 * time: 4.9114227294921875e-5
     1     5.174461e+05     8.708698e+05
 * time: 3.28534197807312
     2     3.865265e+05     6.344302e+05
 * time: 6.624495983123779
     3     1.804274e+05     2.829723e+05
 * time: 9.015691995620728
     4     9.706640e+04     1.550547e+05
 * time: 12.425055027008057
     5     4.769637e+04     6.778818e+04
 * time: 14.47299599647522
     6     2.902319e+04     3.499747e+04
 * time: 17.126474142074585
     7     1.823472e+04     1.705751e+04
 * time: 18.949612140655518
     8     1.258819e+04     9.569381e+03
 * time: 21.18776297569275
     9     9.389984e+03     8.615851e+03
 * time: 24.231640100479126
    10     7.314702e+03     7.636883e+03
 * time: 27.641842126846313
    11     5.916029e+03     6.624325e+03
 * time: 30.89994215965271
    12     4.930519e+03     5.558140e+03
 * time: 34.41958713531494
    13     4.125060e+03     4.315759e+03
 * time: 37.01551699638367
    14     3.549280e+03     3.051093e+03
 * time: 38.910706996917725
    15     3.283489e+03     2.157292e+03
 * time: 40.843899965286255
    16     3.204886e+03     1.659798e+03
 * time: 42.58100509643555
    17     3.194875e+03     1.480528e+03
 * time: 44.34722900390625
    18     3.193944e+03     1.437921e+03
 * time: 46.056424140930176
    19     3.193070e+03     1.411186e+03
 * time: 47.82005500793457
    20     3.190129e+03     1.355327e+03
 * time: 49.63676309585571
    21     3.183228e+03     1.276603e+03
 * time: 51.85410499572754
    22     3.164897e+03     1.151838e+03
 * time: 53.608317136764526
    23     3.119250e+03     9.712651e+02
 * time: 55.51257801055908
    24     3.006297e+03     7.204342e+02
 * time: 58.33063817024231
    25     2.738913e+03     4.050545e+02
 * time: 61.28430700302124
    26     2.123834e+03     2.318194e+02
 * time: 63.04982113838196
    27     1.789139e+03     2.290465e+02
 * time: 64.76023316383362
Warning: Interrupted. Larger maxiters is needed. If you are using an integrator for non-stiff ODEs or an automatic switching algorithm (the default), you may want to consider using a method for stiff equations. See the solver pages for more details (e.g. https://docs.sciml.ai/DiffEqDocs/stable/solvers/ode_solve/#Stiff-Problems).
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:589
Warning: Interrupted. Larger maxiters is needed. If you are using an integrator for non-stiff ODEs or an automatic switching algorithm (the default), you may want to consider using a method for stiff equations. See the solver pages for more details (e.g. https://docs.sciml.ai/DiffEqDocs/stable/solvers/ode_solve/#Stiff-Problems).
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:589
Warning: Terminated early due to NaN in gradient.
@ Optim ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/Optim/7krni/src/multivariate/optimize/optimize.jl:117
Warning: Interrupted. Larger maxiters is needed. If you are using an integrator for non-stiff ODEs or an automatic switching algorithm (the default), you may want to consider using a method for stiff equations. See the solver pages for more details (e.g. https://docs.sciml.ai/DiffEqDocs/stable/solvers/ode_solve/#Stiff-Problems).
@ SciMLBase ~/run/_work/PumasTutorials.jl/PumasTutorials.jl/custom_julia_depot/packages/SciMLBase/JKXkh/src/integrator_interface.jl:589
    28     1.576318e+03     2.147821e+02
 * time: 75.8752830028534
    29     1.380652e+03     1.621863e+02
 * time: 82.60585713386536
    30     1.298107e+03     1.130479e+02
 * time: 84.21117305755615
    31     1.271740e+03     2.292541e+02
 * time: 86.05455613136292
    32     1.255835e+03     1.721669e+02
 * time: 87.56385016441345
    33     1.251089e+03     1.813354e+02
 * time: 88.9577100276947
    34     1.243725e+03     1.920537e+02
 * time: 90.26416206359863
    35     1.241416e+03     1.835909e+02
 * time: 91.55497717857361
    36     1.240510e+03     1.715569e+02
 * time: 92.83500409126282
    37     1.240496e+03     1.710861e+02
 * time: 94.10288500785828
    38     1.240467e+03     1.703009e+02
 * time: 95.39114499092102
    39     1.240383e+03     1.685321e+02
 * time: 96.67335915565491
    40     1.240176e+03     1.649610e+02
 * time: 97.94923400878906
    41     1.239647e+03     1.571549e+02
 * time: 99.2391049861908
    42     1.238394e+03     1.407042e+02
 * time: 100.54514813423157
    43     1.235743e+03     1.084408e+02
 * time: 101.8428521156311
    44     1.231513e+03     5.668753e+01
 * time: 103.1347279548645
    45     1.227771e+03     4.125472e+01
 * time: 104.43070816993713
    46     1.226339e+03     5.546989e+01
 * time: 105.74839615821838
    47     1.226095e+03     4.927853e+01
 * time: 107.03446817398071
    48     1.226086e+03     4.642266e+01
 * time: 108.39001798629761
    49     1.226086e+03     4.611503e+01
 * time: 109.655837059021
    50     1.226081e+03     4.478422e+01
 * time: 110.90723514556885
    51     1.226071e+03     4.294093e+01
 * time: 112.15699601173401
    52     1.226042e+03     3.911828e+01
 * time: 113.39814615249634
    53     1.225973e+03     3.210937e+01
 * time: 114.6512451171875
    54     1.225806e+03     2.839654e+01
 * time: 115.91033101081848
    55     1.225466e+03     2.859127e+01
 * time: 117.1874361038208
    56     1.224959e+03     3.226886e+01
 * time: 118.44062805175781
    57     1.224556e+03     4.925686e+01
 * time: 119.65679001808167
    58     1.224428e+03     4.689186e+01
 * time: 120.89305996894836
    59     1.224411e+03     4.101617e+01
 * time: 122.1394419670105
    60     1.224410e+03     3.916788e+01
 * time: 123.3904709815979
    61     1.224408e+03     3.787270e+01
 * time: 124.62512111663818
    62     1.224402e+03     3.519636e+01
 * time: 125.8683819770813
    63     1.224389e+03     3.233949e+01
 * time: 127.1176209449768
    64     1.224351e+03     3.054354e+01
 * time: 128.36957502365112
    65     1.224256e+03     2.816053e+01
 * time: 129.59323811531067
    66     1.224007e+03     2.821380e+01
 * time: 130.79788613319397
    67     1.223382e+03     3.119472e+01
 * time: 132.04598999023438
    68     1.221919e+03     6.976985e+01
 * time: 133.3021581172943
    69     1.219110e+03     1.073633e+02
 * time: 134.48325395584106
    70     1.215576e+03     1.072842e+02
 * time: 135.6565191745758
    71     1.213034e+03     8.400960e+01
 * time: 136.8380229473114
    72     1.212294e+03     8.951044e+01
 * time: 137.99933505058289
    73     1.212259e+03     8.933198e+01
 * time: 139.31241917610168
    74     1.212255e+03     8.895637e+01
 * time: 141.43333911895752
    75     1.212241e+03     8.777217e+01
 * time: 142.7583041191101
    76     1.212214e+03     8.600288e+01
 * time: 143.95316815376282
    77     1.212135e+03     8.213714e+01
 * time: 145.17366409301758
    78     1.211943e+03     7.451404e+01
 * time: 146.41006803512573
    79     1.211464e+03     5.844663e+01
 * time: 147.6479320526123
    80     1.210406e+03     6.363959e+01
 * time: 148.907466173172
    81     1.208527e+03     7.916604e+01
 * time: 150.14459800720215
    82     1.206464e+03     8.366506e+01
 * time: 151.37343311309814
    83     1.205476e+03     1.005964e+02
 * time: 152.57710099220276
    84     1.205305e+03     8.882827e+01
 * time: 153.86396312713623
    85     1.205293e+03     8.309057e+01
 * time: 155.98372507095337
    86     1.205290e+03     8.172481e+01
 * time: 157.8416690826416
    87     1.205275e+03     7.814716e+01
 * time: 160.68673396110535
    88     1.205243e+03     7.364643e+01
 * time: 163.40357899665833
    89     1.205155e+03     6.632764e+01
 * time: 165.3884620666504
    90     1.204934e+03     6.325952e+01
 * time: 167.34593796730042
    91     1.204369e+03     5.693461e+01
 * time: 168.81090211868286
    92     1.203050e+03     5.234111e+01
 * time: 170.2762429714203
    93     1.200504e+03     5.128249e+01
 * time: 171.75390005111694
    94     1.197282e+03     7.013671e+01
 * time: 173.0772099494934
    95     1.194826e+03     5.064375e+01
 * time: 174.39608001708984
    96     1.193905e+03     4.851059e+01
 * time: 175.6990361213684
    97     1.193833e+03     4.996663e+01
 * time: 177.0233919620514
    98     1.193831e+03     5.008119e+01
 * time: 178.30627012252808
    99     1.193829e+03     5.013190e+01
 * time: 179.52727794647217
   100     1.193824e+03     5.022328e+01
 * time: 180.90246295928955
   101     1.193812e+03     5.034993e+01
 * time: 182.53406715393066
   102     1.193779e+03     5.053003e+01
 * time: 183.81674003601074
   103     1.193695e+03     5.072909e+01
 * time: 185.03127908706665
   104     1.193477e+03     5.080775e+01
 * time: 186.25265216827393
   105     1.192938e+03     5.030899e+01
 * time: 187.47217917442322
   106     1.191706e+03     4.810245e+01
 * time: 188.71226596832275
   107     1.189391e+03     4.971073e+01
 * time: 189.92632794380188
   108     1.186449e+03     8.056474e+01
 * time: 191.15317797660828
   109     1.184524e+03     9.072066e+01
 * time: 192.4037640094757
   110     1.184030e+03     8.460397e+01
 * time: 193.66602301597595
   111     1.183978e+03     7.969454e+01
 * time: 194.8899290561676
   112     1.183972e+03     7.815446e+01
 * time: 196.09582495689392
   113     1.183968e+03     7.789814e+01
 * time: 197.2997109889984
   114     1.183964e+03     7.808136e+01
 * time: 198.54501509666443
   115     1.183956e+03     7.875580e+01
 * time: 199.7967700958252
   116     1.183938e+03     8.003236e+01
 * time: 201.046972990036
   117     1.183894e+03     8.217667e+01
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 * time: 611.6056251525879
   359     1.067991e+03     9.459425e-02
 * time: 613.6342561244965
   360     1.067991e+03     9.459425e-02
 * time: 615.6277520656586
   361     1.067991e+03     9.459425e-02
 * time: 618.2075991630554
   362     1.067991e+03     9.459426e-02
 * time: 620.5964889526367
   363     1.067991e+03     9.459426e-02
 * time: 623.0132110118866
   364     1.067991e+03     9.459426e-02
 * time: 625.4707181453705
   365     1.067991e+03     9.459426e-02
 * time: 627.5397300720215
   366     1.067991e+03     9.459426e-02
 * time: 629.6662740707397
   367     1.067991e+03     9.459426e-02
 * time: 631.7079780101776
   368     1.067991e+03     9.459426e-02
 * time: 633.9353420734406
   369     1.067991e+03     9.459426e-02
 * time: 637.1764481067657
   370     1.067991e+03     9.459426e-02
 * time: 640.0038540363312
   371     1.067991e+03     9.459426e-02
 * time: 642.1507339477539
   372     1.067991e+03     9.459426e-02
 * time: 642.6700010299683
FittedPumasModel

Dynamical system type:               Nonlinear ODE
Solver(s):              OrdinaryDiffEqVerner.Vern7

Number of subjects:                             32

Observation records:         Active        Missing
    conc:                       251             47
    pca:                        232             66
    Total:                      483            113

Number of parameters:      Constant      Optimized
                                  0             18

Likelihood approximation:                     FOCE
Likelihood optimizer:                         BFGS

Termination Reason:                      NoXChange
Log-likelihood value:                   -1067.9913

-----------------------
            Estimate
-----------------------
pop_CL       0.13521
pop_V        8.0133
pop_tabs     0.57114
pop_lag      0.87561
pop_e0      96.399
pop_emax    -1.0615
pop_c50      1.4912
pop_tover   14.05
pk_Ω₁,₁      0.068012
pk_Ω₂,₂      0.021048
pk_Ω₃,₃      0.86273
pd_Ω₁,₁      0.002977
pd_Ω₂,₂      1.9398e-7
pd_Ω₃,₃      0.14561
pd_Ω₄,₄      0.015351
σ_prop       0.088485
σ_add        0.41684
σ_fx         3.5803
-----------------------

8 Concluding Remarks

In this tutorial, you have seen how to adjust the tolerances and the algorithm of the differential solver. Usually, the default differential equation solver in Pumas is an efficient choice. To reduce numerical issues, sometimes it can be helpful to decrease the default tolerances.