Midpoint vs Trapeze

Note
  • The linear solver is MUMPS for CPU experiments and CUDSS for GPU experiments.
  • Below you can find Dolan–Moré performance profiles comparing discretization method–solver combinations on the set of optimal control problems. For a detailed explanation of how to read these profiles, see the Performance Profiles page.

Comparison of Discretization Methods

This benchmark evaluates the effect of two discretization methods:

  • Midpoint
  • Trapeze

combined with two nonlinear solvers:

  • Ipopt
  • MadNLP

on the ExaModels optimal control modeler.

The comparison is based on four combinations (disc_method, solver):

  1. (trapeze, ipopt)
  2. (trapeze, madnlp)
  3. (midpoint, ipopt)
  4. (midpoint, madnlp)

⚙️ Configuration

  • Problems: balanced_field, beam, brachistochrone, bryson_denham, chain, dielectrophoretic_particle, double_oscillator, ducted_fan, electric_vehicle, glider, insurance, jackson, mountain_car, robbins, robot, rocket, space_shuttle, steering, vanderpol

  • Solvers: ipopt, madnlp

  • Models: exa

  • Grid sizes: 200 discretization points

  • Discretization: trapeze, midpoint method

  • Tolerance: 1.0e-8

  • Ipopt strategy: adaptive barrier parameter

  • Limits: 2000 iterations max, 600.0s wall time

🖥️ Environment

📅 Timestamp     : 2026-03-10 19:11:59 UTC
🔧 Julia version : 1.12.5
💻 OS            : Linux
🖥️ Machine       : runnervm0kj6c

You can download the exact environment used for this benchmark:

These files allow you to reproduce the benchmark environment and results exactly.

Julia Version 1.12.5
Commit 5fe89b8ddc1 (2026-02-09 16:05 UTC)
Build Info:
  Official https://julialang.org release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 4 × AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, znver3)
  GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 4 virtual cores)
Environment:
  JULIA_PKG_SERVER_REGISTRY_PREFERENCE = eager
Project CTBenchmarks v0.3.1
Status `~/work/CTBenchmarks.jl/CTBenchmarks.jl/Project.toml`
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Info Packages marked with  have new versions available but compatibility constraints restrict them from upgrading. To see why use `status --outdated`
Project CTBenchmarks v0.3.1
Status `~/work/CTBenchmarks.jl/CTBenchmarks.jl/Manifest.toml`
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Info Packages marked with  and  have new versions available. Those with  may be upgradable, but those with  are restricted by compatibility constraints from upgrading. To see why use `status --outdated -m`

📈 Performance Profile: CPU Time

Performance Profile Analysis

Dataset overview for core-midpoint-trapeze:

  • Problems: 19 unique optimal control problems
  • Instances: 19
  • Solver combos: 4

Profile configuration:

  • Instance definition: (problem, grid_size)
  • Solver combos definition: (disc_method, solver)
  • Criterion: CPU time
  • Successful runs: 76/76 (100.0%)
  • Successful instances: 19/19 (100.0%)
  • Unsuccessful instances: none (every instance had at least one successful run)

Robustness (% of instances solved):

  • (trapeze, madnlp): 100.0%
  • (midpoint, madnlp): 100.0%
  • (trapeze, ipopt): 100.0%
  • (midpoint, ipopt): 100.0%

Efficiency (% of instances where fastest):

  • (trapeze, madnlp): 36.8%
  • (midpoint, madnlp): 57.9%
  • (trapeze, ipopt): 0.0%
  • (midpoint, ipopt): 5.3%

Most robust: 4 combinations tied at 100.0%.

Most efficient: (midpoint, madnlp) was fastest on 57.9% of instances.

📊 Result Tables


SuccessNModelSolverTime (ms)ItersObjectiveCriterionBest
200exaipopt38.69317771.011400min
200exaipopt39.51719771.009269min
200examadnlp39.57623771.011400min
200examadnlp35.45923771.009269min
Benchmarks results:

┌─ Problem: balanced_field
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  39.576 ms | iters: 23    | obj: 7.710114e+02  (min) | CPU:   5.62 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  35.459 ms | iters: 23    | obj: 7.710093e+02  (min) | CPU:   5.32 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  38.693 ms | iters: 17    | obj: 7.710114e+02  (min) | CPU: 129.11 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  39.517 ms | iters: 19    | obj: 7.710093e+02  (min) | CPU: 127.05 KiB
│  └─
└─

┌─ Problem: beam
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  12.026 ms | iters: 21    | obj: 8.891335e+00  (min) | CPU:   1.76 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  15.034 ms | iters: 23    | obj: 8.889505e+00  (min) | CPU:   1.79 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  15.385 ms | iters: 16    | obj: 8.891335e+00  (min) | CPU:  72.55 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  13.688 ms | iters: 15    | obj: 8.889505e+00  (min) | CPU:  70.39 KiB
│  └─
└─

┌─ Problem: brachistochrone
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  23.718 ms | iters: 20    | obj: 1.802935e+00  (min) | CPU:   2.88 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  22.065 ms | iters: 20    | obj: 1.802937e+00  (min) | CPU:   2.55 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  30.834 ms | iters: 19    | obj: 1.802935e+00  (min) | CPU:  96.05 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  27.339 ms | iters: 19    | obj: 1.802937e+00  (min) | CPU:  95.20 KiB
│  └─
└─

┌─ Problem: bryson_denham
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   8.606 ms | iters: 15    | obj: 4.000889e+00  (min) | CPU:   1.33 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   9.666 ms | iters: 15    | obj: 4.000222e+00  (min) | CPU:   1.26 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  12.450 ms | iters: 13    | obj: 4.000889e+00  (min) | CPU:  69.45 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  11.768 ms | iters: 13    | obj: 4.000222e+00  (min) | CPU:  68.33 KiB
│  └─
└─

┌─ Problem: chain
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   8.091 ms | iters: 7     | obj: 5.068917e+00  (min) | CPU:   1.43 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  11.629 ms | iters: 12    | obj: 5.068486e+00  (min) | CPU:   1.37 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   9.618 ms | iters: 7     | obj: 5.068917e+00  (min) | CPU:  70.12 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  13.676 ms | iters: 12    | obj: 5.068486e+00  (min) | CPU:  72.94 KiB
│  └─
└─

┌─ Problem: dielectrophoretic_particle
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   9.163 ms | iters: 13    | obj: 7.811387e+00  (min) | CPU:   1.95 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   9.374 ms | iters: 14    | obj: 7.811390e+00  (min) | CPU:   1.75 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  13.032 ms | iters: 12    | obj: 7.811387e+00  (min) | CPU:  72.77 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  13.401 ms | iters: 13    | obj: 7.811390e+00  (min) | CPU:  72.48 KiB
│  └─
└─

┌─ Problem: double_oscillator
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   8.216 ms | iters: 5     | obj: 9.103362e-04  (min) | CPU:   2.71 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   7.183 ms | iters: 5     | obj: 9.101904e-04  (min) | CPU:   2.11 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  11.214 ms | iters: 5     | obj: 9.103362e-04  (min) | CPU: 102.86 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   9.673 ms | iters: 5     | obj: 9.101904e-04  (min) | CPU: 100.23 KiB
│  └─
└─

┌─ Problem: ducted_fan
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 154.004 ms | iters: 41    | obj: 1.831942e+03  (min) | CPU:   9.51 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 140.925 ms | iters: 48    | obj: 1.831890e+03  (min) | CPU:  10.14 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 487.905 ms | iters: 92    | obj: 1.831942e+03  (min) | CPU: 254.80 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 390.539 ms | iters: 91    | obj: 1.831890e+03  (min) | CPU: 252.38 KiB
│  └─
└─

┌─ Problem: electric_vehicle
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   3.665 ms | iters: 4     | obj: 1.228699e+03  (min) | CPU:   1.33 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   3.832 ms | iters: 4     | obj: 1.228639e+03  (min) | CPU:   1.03 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   4.549 ms | iters: 4     | obj: 1.228699e+03  (min) | CPU:  58.38 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   4.365 ms | iters: 4     | obj: 1.228639e+03  (min) | CPU:  54.53 KiB
│  └─
└─

┌─ Problem: glider
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 318.623 ms | iters: 112   | obj: -1.248896e+03 (min) | CPU:  14.30 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  71.498 ms | iters: 30    | obj: -1.247918e+03 (min) | CPU:   6.57 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 324.474 ms | iters: 78    | obj: -1.248896e+03 (min) | CPU: 268.72 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 118.511 ms | iters: 38    | obj: -1.247918e+03 (min) | CPU: 219.34 KiB
│  └─
└─

┌─ Problem: insurance
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 340.188 ms | iters: 120   | obj: -2.058581e+00 (min) | CPU:  26.32 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 369.592 ms | iters: 124   | obj: -2.057424e+00 (min) | CPU:  24.74 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 340.853 ms | iters: 91    | obj: -2.058581e+00 (min) | CPU: 246.09 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   3.409 s  | iters: 143   | obj: -2.057424e+00 (min) | CPU: 297.06 KiB
│  └─
└─

┌─ Problem: jackson
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  49.681 ms | iters: 40    | obj: -1.918610e-01 (min) | CPU:   6.74 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  37.486 ms | iters: 33    | obj: -1.918402e-01 (min) | CPU:   5.55 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  81.991 ms | iters: 42    | obj: -1.918613e-01 (min) | CPU: 124.73 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  87.101 ms | iters: 48    | obj: -1.918405e-01 (min) | CPU: 126.94 KiB
│  └─
└─

┌─ Problem: mountain_car
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  53.628 ms | iters: 49    | obj: 1.023810e+02  (min) | CPU:   5.51 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  34.204 ms | iters: 39    | obj: 1.023848e+02  (min) | CPU:   4.48 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  63.619 ms | iters: 41    | obj: 1.023976e+02  (min) | CPU: 100.95 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  53.776 ms | iters: 39    | obj: 1.023848e+02  (min) | CPU:  97.86 KiB
│  └─
└─

┌─ Problem: robbins
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  26.868 ms | iters: 34    | obj: 1.962626e+01  (min) | CPU:   2.65 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  23.565 ms | iters: 19    | obj: 1.945946e+01  (min) | CPU:   1.92 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  23.580 ms | iters: 19    | obj: 1.962626e+01  (min) | CPU:  95.61 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  21.396 ms | iters: 19    | obj: 1.945946e+01  (min) | CPU:  94.50 KiB
│  └─
└─

┌─ Problem: robot
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  49.394 ms | iters: 16    | obj: 9.141397e+00  (min) | CPU:   6.61 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  45.145 ms | iters: 16    | obj: 9.140868e+00  (min) | CPU:   6.25 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  65.674 ms | iters: 18    | obj: 9.141395e+00  (min) | CPU: 181.27 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  52.621 ms | iters: 15    | obj: 9.140867e+00  (min) | CPU: 175.55 KiB
│  └─
└─

┌─ Problem: rocket
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  22.603 ms | iters: 21    | obj: -1.012835e+00 (min) | CPU:   4.41 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  22.132 ms | iters: 22    | obj: -1.012837e+00 (min) | CPU:   4.27 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  28.546 ms | iters: 18    | obj: -1.012836e+00 (min) | CPU: 101.02 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  25.799 ms | iters: 17    | obj: -1.012838e+00 (min) | CPU:  98.86 KiB
│  └─
└─

┌─ Problem: space_shuttle
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 938.387 ms | iters: 181   | obj: -5.958694e-01 (min) | CPU:  52.66 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 332.089 ms | iters: 74    | obj: -5.958757e-01 (min) | CPU:  24.64 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 722.335 ms | iters: 101   | obj: -5.958694e-01 (min) | CPU: 309.17 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time: 708.524 ms | iters: 106   | obj: -5.958757e-01 (min) | CPU: 305.33 KiB
│  └─
└─

┌─ Problem: steering
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  17.811 ms | iters: 11    | obj: 5.545770e-01  (min) | CPU:   2.35 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  16.099 ms | iters: 10    | obj: 5.545724e-01  (min) | CPU:   2.12 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  18.921 ms | iters: 8     | obj: 5.545770e-01  (min) | CPU: 102.95 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:  18.292 ms | iters: 8     | obj: 5.545724e-01  (min) | CPU: 101.83 KiB
│  └─
└─

┌─ Problem: vanderpol
│
├──┬ Solver: madnlp, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   2.817 ms | iters: 3     | obj: 1.047836e+00  (min) | CPU:   1.33 MiB
│  └─
│
├──┬ Solver: madnlp, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   3.838 ms | iters: 3     | obj: 1.047802e+00  (min) | CPU:   1.08 MiB
│  └─
│
├──┬ Solver: ipopt, Discretization: trapeze
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   3.680 ms | iters: 3     | obj: 1.047836e+00  (min) | CPU:  53.50 KiB
│  └─
│
├──┬ Solver: ipopt, Discretization: midpoint
│  │
│  │  N = 200
│  │  ✓ | exa      | time:   3.897 ms | iters: 3     | obj: 1.047802e+00  (min) | CPU:  52.19 KiB
│  └─
└─