MatthewPeterKelly / MatthewPeterKelly/OptimTraj

GPOPS-II Interpolation Function Handle returned by OptimTraj

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enhancement help wanted question
Dominant language
MATLAB
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Description

In gpopsWrapper.m, OptimTraj provides an interpolation function handle for the GPOPS-II solution using pchip, as per the code below. Is pchip the most accurate way to interpolate the GPOPS-II solution?

soln.interp.state = @(t)( interp1(tSoln',xSoln',t','pchip',nan)' );
soln.interp.control = @(t)( interp1(tSoln',uSoln',t','pchip',nan)' );

The formula for the GPOPS-II state is given in equation (25) of the GPOPS-II paper:

Patterson, Michael A., and Anil V. Rao. "GPOPS-II: A MATLAB software for solving multiple-phase optimal control problems using hp-adaptive Gaussian quadrature collocation methods and sparse nonlinear programming." ACM Transactions on Mathematical Software (TOMS) 41.1 (2014): 1.

http://dl.acm.org/citation.cfm?id=2558904

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Research direction

Start with gpopsWrapper.m and inspect the soln.interp.state and soln.interp.control handles that call interp1 with pchip. Read equation (25) of the cited GPOPS-II paper, then determine whether the current interpolation matches the stated solution representation. Done requires a clear conclusion about the interpolation approach and any corresponding update to the function handles.

Written by the indexing model from the issue text.

Assessment

Tech stack
matlab
Domain
tooling
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
20/100

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