[Steven-Roberts]

Description

This is a draft of a partitioned DAE integrator interface. It currently uses masking of the residual and Jacobian, with many TODO statement indicating where things will need to be updated when GridKit partitioning functionality is in place.

It requires this branch of SUNDIALS: https://github.com/llnl/sundials/tree/feature/partitioned-dae-stepper

Proposed changes

Adds a new DynamicSolver and a unit test on a simple 5 variable DAE.

Checklist

• All tests pass.
• Code compiles cleanly with flags -Wall -Wpedantic -Wconversion -Wextra.
• The new code follows GridKit™ style guidelines.
• There are unit tests for the new code.
• The new code is documented.
• The feature branch is rebased with respect to the target branch.
• The CHANGELOG.md has been updated to reflect the changes. If this is a minor PR that is part of a larger fix already included in the file, state so.

[read-the-docs-community]

Documentation build overview

📚 GridKit | 🛠️ Build #35344458 | 📁 Comparing 1100844 against latest (4315301)

  🔍 Preview build  

16 files changed · + 5 added · ± 11 modified

+ Added

• api/reference/classAnalysisManager_1_1Sundials_1_1Partitioned.html
• api/reference/classAnalysisManager_1_1Sundials_1_1PartitionedException.html
• api/reference/file_GridKit_Solver_Dynamic_Partitioned.hpp.html
• api/reference/structAnalysisManager_1_1Sundials_1_1PartitionedStats.html
• api/reference/typedef_namespaceAnalysisManager_1_1Sundials_1ad0e4c101846e24e867d3337c0c081a2d.html

± Modified

• genindex.html
• api/reference/classAnalysisManager_1_1DynamicSolver.html
• api/reference/dir_GridKit_Solver_Dynamic.html
• api/reference/file_GridKit_AutomaticDifferentiation_DependencyTracking_VariableOperators.hpp.html
• api/reference/file_GridKit_Model_Evaluator.hpp.html
• api/reference/file_GridKit_Model_PhasorDynamics_SystemModelData.hpp.html
• api/reference/file_GridKit_Solver_Dynamic_DynamicSolver.hpp.html
• api/reference/file_GridKit_Testing_Testing.hpp.html
• api/reference/namespace_AnalysisManager__Sundials.html
• api/reference/namespace_GridKit__DependencyTracking.html
• and 1 more...

[pelesh]

The PartitionedTest test segfaults in my case.

1/1 Test #52: PartitionedTest ..................***Exception: SegFault  0.03 sec

Here is the backtrace:

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x8)
  * frame #0: 0x00000001001b2870 libsundials_idas.6.dylib`IDASetLinearSolver(ida_mem=0x000000012b008e00, LS=<unavailable>, A=0x0000000000000000) at idas_ls.c:130:28 [opt]
    frame #1: 0x000000010007797c libgridkit_solvers_dyn.0.dylib`AnalysisManager::Sundials::Partitioned<double, unsigned long>::configurePartitionSolvers(this=0x000000016fdfe240) at Partitioned.cpp:366:21 [opt]
    frame #2: 0x00000001000757fc libgridkit_solvers_dyn.0.dylib`AnalysisManager::Sundials::Partitioned<double, unsigned long>::createSolver(this=0x000000016fdfe240, t0=<unavailable>) at Partitioned.cpp:336:7 [opt]
    frame #3: 0x00000001000755b8 libgridkit_solvers_dyn.0.dylib`AnalysisManager::Sundials::Partitioned<double, unsigned long>::initializeSimulation(this=0x000000016fdfe240, t0=0) at Partitioned.cpp:92:7 [opt]
    frame #4: 0x0000000100006fd8 test_partitioned`GridKit::Testing::PartitionedTests<double, unsigned long>::integration(this=0x000000016fdfe78b) at PartitionedTests.hpp:362:16 [opt]
    frame #5: 0x0000000100006e78 test_partitioned`main at runPartitionedTests.cpp:7:18 [opt]
    frame #6: 0x000000019155ab98 dyld`start + 6076
(lldb) 

[pelesh]

This looks very good and the test passes.

I suggest to start separating interface to partitioned solver from the solver implementation as suggested below. That will help make it more clear what should API for partitioned solvers look like.

[pelesh]

I would use GridKit's isEqual helper function.

[pelesh]

I suggest Implementing helper classes and structs in separate files. Files Partitioned*pp should contain interface to the solver. The solver itself should be implemented in files located in Partitioned subdirectory.

[nkoukpaizan]

I recommend adding some minimal documentation of the methods. We'll likely iterate on the function signatures, so just a high-level description of that they do.

Good to merge after the minor comments have been addressed.