Improvements for Degeneracy Hunter 2

[adowling2]

PR #149, issue #71, and PR IDAES/examples-pse#21 track the "beta" version of Degeneracy Hunter (to be tested during the Spring 2021 semester).

This issue is to track planned improvements for Degeneracy Hunter for the official release. Wishlist:

• [x] Refactor code (including reorganizing classes, remove static methods)
• [ ] Update documentation page
  • [ ] Mathematical formulation
  • [ ] Motivating example?
  • [ ] Link to other examples
• [ ] Revisit how to extend degeneracy hunter to active bounds/inequality constraints
• [ ] Add support for fixed variables
  • [ ] Prepare example with fixed variables. Test what happens.
  • [ ] If needed, remove columns from the Jacobian that correspond to fixed variable
• [x] How should this interface with the IDAES model scaling features?
• [ ] Add tests to pynumero to ensure the required API calls do not change (or lobby for IDAES to check against Pyomo master every night/week)
• [x] Add cbc to the testing harness
• [x] Add unit tests for degeneracy hunter (needs MILP solver)
• [ ] Add example(s) that uses IDAES model. Possible option: distillation column example from @jghouse88 with extra pressure constraints.
• [x] Add test(s) that uses IDAES model
• [ ] Add example/test for loading Jacobian from a file
• [ ] Test/address scalability
• [x] Use IDAES logger
• [x] Check compliance with PEP8
• [ ] Enhance tests by capturing and analyzing printed output
• [x] Use ConfigDict (available in Pyomo) or similar to handle specifications include MILP solver

Goal: address these improvements in Summer or Fall 2021

[dallan-keylogic]

What is the status of these improvements, @adowling2 ? In particular, does the current version of Degeneracy Hunter support fixed variables? I'm finding that a certain IDAES model has a rank deficient Jacobian, but that information is significantly less useful if those degrees of freedom are defined by fixed variables instead.

[andrewlee94]

At least some of these were addressed when Degeneracy Hunter was incorporated into the Diagnostics Toolbox.