Some Birkhoff constraints are now treated as linear. #1043
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The state segment end values are no longer a variable in the birkhoff transcription. Birkhoff linear constraints are now improving sparsity on a lot of problems. Fixed an issue with abs/promoted path names for timeseries plotting.
…ile, simulation and solution cases do not match.
…but needs derivatives and polynomials to work also
… derivative matrices when n is not high enough.
… have no higher order derivatives
…rmat to coo so that data is a contiguous 1D array.
kaushikponnapalli
approved these changes
Mar 11, 2024
| @@ -33,7 +33,7 @@ class BirkhoffCollocationComp(om.ExplicitComponent): | |||
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| def __init__(self, **kwargs): | |||
| super().__init__(**kwargs) | |||
| self._no_check_partials = not dymos_options['include_check_partials'] | |||
| # self._no_check_partials = not dymos_options['include_check_partials'] | |||
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Summary
The dense block in the Birkhoff transcription's sparsity pattern is due to a matrix used to compute the state defects as a function of the state rates. This matrix is constant and, as long as the states are a design variable, this constraint is linear.
Making this constraint linear significantly improves the sparsity coloring for the Phase. The Birkhoff transcription maintains the sparsity, and good conditioning, even when the number of nodes is extremely high.
There were several changes to tests since Birkhoff doesn't have a notion of segments anymore.
The timeseries output come was providing noisy derivatives with higher orders (really small but nonzero noise).
Now it behaves as a passthru if no interpolation is being performed.
Related Issues
Backwards incompatibilities
None
New Dependencies
None