MatthewPeterKelly/OptimTraj

Bug (?) in OptimTraj wrapper for GPOPS?

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#19 opened on Sep 9, 2016

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bughelp wanted

Description

I'm having some trouble getting the OptimTraj gpops method to work on my problem in certain cases. Do you know what might be causing the error below? I think this error may be related to how OptimTraj wraps GPOPS-II, because whenever I use GPOPS-II independently from OptimTraj on my optimal control problem, I never get this error.

| | | Finding Solution on Mesh 2 | |___________________________________________________________________| Computing Radau Points, Integration Weights, and Integration Matrix Creating Bounds For Nonlinear Program Creating Guess For Nonlinear Program Error using griddedInterpolant Interpolation requires at least two sample points in each dimension.

Error in interp1 (line 161) F = griddedInterpolant(X,V,method);

Error in gpopsGuessRPMI

Error in gpopsSolveRPMI

Error in gpopsMeshShell

Error in gpops2

Error in gpopsWrapper (line 84) output = gpops2(setup);

Error in optimTraj (line 190) soln(iter) = gpopsWrapper(P);

Error in invoke_OptimTraj (line 176) soln = optimTraj(problem);

Contributor guide

Tech stack
None
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
MATLAB proficiencyOptimal control basicsGPOPS II knowledge
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Investigate the gpopsGuessRPMI function in the OptimTraj repository to understand how the guess is constructed for the NLP. Check why interp1 is called with fewer than two sample points, likely due to an empty or single element vector. The issue might be related to mesh refinement on the second mesh. Compare with GPOPS II standalone to identify differences in the wrapper.