Sparse Jacobians for DVGeometryMulti

[sseraj]

Purpose

I changed the total Jacobian computation in DVGeometryMulti to use sparse matrices instead of dense matrices. I followed one of SciPy's recommended approaches by using lil_matrix for construction and then converting to csr_matrix for faster arithmetic. This approach required minimal changes to the code.

The memory usage was not dramatically different for the cases I tested because the Jacobian is usually not very sparse. Still, the memory used by the sparse Jacobian was about 60% of the memory used by the dense Jacobian for the largest case I tested (around 140k surface points and 270 geometric DVs).

Expected time until merged

1 week

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

The current DVGeometryMulti test passes, which shows that the derivatives are still correct.

Checklist

• I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation

[codecov]

Codecov Report

Merging #187 (49d6108) into main (b7f1bfb) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #187   +/-   ##
=======================================
  Coverage   64.76%   64.77%           
=======================================
  Files          47       47           
  Lines       11949    11951    +2     
=======================================
+ Hits         7739     7741    +2     
  Misses       4210     4210           

Impacted Files	Coverage Δ
pygeo/parameterization/DVGeoMulti.py	91.05% <100.00%> (+0.01%)	⬆️

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[marcomangano]

Nice