[Temp] V2 Review DAE 3 Rosenbrock integration by boulderdaze · Pull Request #927 · NCAR/micm

boulderdaze · 2026-02-11T05:25:42Z

This draft provides the full diffs between DAE 3 and main. Will be closed without review process

Introduces the constraint class hierarchy for algebraic constraints in DAE (Differential-Algebraic Equation) systems: - Constraint: Abstract base class defining the interface - EquilibriumConstraint: Implements equilibrium relationships (K_eq = products/reactants) - ConstraintSet: Manager for collections of constraints with Jacobian support Includes comprehensive unit tests for all constraint functionality. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Prepares the solver infrastructure to support algebraic constraints: State changes: - Add number_of_constraints_ to StateParameters - Add constraint_size_ and upper_left_identity_diagonal_ to State - Size jacobian for species + constraints SolverBuilder changes: - Add SetConstraintCount() and SetConstraintNames() methods - Update Build() to include constraint variables in state This is backward compatible - when constraint_count_=0 (default), behavior is unchanged from before. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Completes the DAE constraint system by wiring constraints into the Rosenbrock solver loop: Solver changes: - Add ConstraintSet member to RosenbrockSolver - Call AddForcingTerms() and SubtractJacobianTerms() in solve loop - Add SetConstraints() to SolverBuilder with full Build() integration Key implementation details: - AlphaMinusJacobian adds alpha to ALL diagonals (ODE and algebraic) - This treats algebraic constraints as stiff ODEs (ε*z' = g with ε=hγ) - Constraint Jacobian elements merged with ODE elements at build time Integration tests: - test_equilibrium.cpp demonstrates working DAE equilibrium solving Documentation: - ARCHITECTURE.md: Implementation details and sign conventions - TESTS.md: Test case specifications - CLAUDE.md: Project context and build instructions - Custom Claude Code skills for testing and debugging Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

@param

- Add educational walkthrough of Constraint, EquilibriumConstraint, and ConstraintSet classes (constraint_classes_walkthrough.md) - Add line-by-line explanation of reactant loop indexing logic (reactant_loop_explanation.md) - Add comparison of ProcessSet vs ConstraintSet Jacobian computation (forcing_jacobian_parallel.md) - Fix incorrect @param comments in Constraint base class - Remove unused <map> include from constraint.hpp Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Use consistent notation across documentation and code: - y for state variables - F(y) for forcing (uppercase) - G(y) for constraints (uppercase) Add note on DAE notation conventions explaining the y/z distinction from DAE literature and why MICM uses a unified state vector. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Rename reactant_loop_explanation.md to indexing_patterns.md to better reflect its broader scope. Add detailed comparison of 2-level indirection (ProcessSet) vs 3-level indirection (Constraint classes), explaining: - How ProcessSet pre-computes global indices at construction - How Constraint receives indices as a parameter for decoupling - The ConstraintSet bridge that connects them - Performance implications and potential optimization paths - Design philosophy trade-offs (OO vs data-oriented) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Architecture Overview section: - Data flow diagram showing how constraints integrate with solver - Component responsibilities for Constraint, EquilibriumConstraint, ConstraintSet, and Rosenbrock Solver - Parallel structure comparison of ProcessSet and ConstraintSet Test Coverage section: - Summary table of EquilibriumConstraint tests - Summary table of ConstraintSet tests - Key scenarios covered by each test suite - Notes on what's not yet tested (future work) - Instructions for running constraint tests Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

New section "Flat Array Memory Layout and Strides" explains: - How MICM uses flat arrays with stride-based access - Dense matrix access pattern (rows=cells, cols=species) - Sparse Jacobian access via AsVector() and FlatBlockSize() - Pre-computed jacobian_flat_ids_ for efficient sparse access - Note that vectorized variants exist in ProcessSet but not yet in ConstraintSet (planned for future optimization) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Rename to constraintset_mirrors_processset.md to better describe the document's purpose: showing how ConstraintSet mirrors ProcessSet's design for Jacobian computation. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Move documentation files from root to docs/design/ - Remove branch name reference from walkthrough intro - Replace std::pair<std::string, double> with Yield type for reactants_ and products_ in EquilibriumConstraint - Fix dead code in Jacobian calculation (removed unused assignment) - Update test files to use Yield(Species(...), coeff) syntax Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add MICM_ERROR_CATEGORY_CONSTRAINT and error codes to error.hpp - Create constraint_error.hpp with MicmConstraintErrc enum and error category - Replace std::invalid_argument with std::system_error in EquilibriumConstraint - Replace std::runtime_error with std::system_error in ConstraintSet - Update tests to expect std::system_error Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Address PR feedback from K20shores and Copilot regarding performance: - K20shores (line 199): "make Residual operate on the dense matrix directly" - K20shores (line 247): "agreed" with Copilot on SubtractJacobianTerms Refactor Residual() and Jacobian() to use pointers instead of vectors, eliminating temporary allocations in the inner grid cell loop: - Change Constraint interface from vector-based to pointer-based - Add dependency_offset_ and jacobian_flat_offset_ to ConstraintInfo for O(1) access to pre-computed index arrays - Add max_dependencies_ for reusable Jacobian buffer allocation - AddForcingTerms: access row data directly via &cell_state[0] - SubtractJacobianTerms: use single reusable jac_buffer across all constraints and grid cells Performance impact: - Eliminates per-cell vector copy of concentrations (was N species) - Eliminates per-constraint vector copy of indices - Eliminates per-constraint Jacobian vector allocation Update documentation to reflect the new interface. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Address Copilot review suggestions: - Validate reactants is not empty (EmptyReactants error) - Validate products is not empty (EmptyProducts error) - Validate all stoichiometric coefficients are positive (InvalidStoichiometry error) Adds corresponding error codes and test cases. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

…tion

remove md files, and update the test names

…tion

…nbrock-integration

codecov-commenter · 2026-02-11T06:24:23Z

Codecov Report

❌ Patch coverage is 95.40230% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.66%. Comparing base (1c6b2ed) to head (4a899b3).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
include/micm/solver/rosenbrock.inl	78.94%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #927      +/-   ##
==========================================
+ Coverage   94.63%   94.66%   +0.03%     
==========================================
  Files          68       68              
  Lines        3185     3487     +302     
==========================================
+ Hits         3014     3301     +287     
- Misses        171      186      +15

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Copilot

Pull request overview

This PR introduces initial plumbing for algebraic constraints (DAE-style) into the CPU solver stack, including a new Constraint/ConstraintSet API, solver-builder wiring, and an integration test that exercises the new builder API.

Changes:

Add Constraint (variant wrapper), ConstraintSet, and integrate constraint Jacobian/forcing contributions into Rosenbrock solve setup.
Extend State/StateParameters with constraint-related metadata and build Jacobians sized for species + constraint rows.
Add a new integration test target (equilibrium) and update existing unit tests to use the new constraint container types.

Reviewed changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
`include/micm/constraint/constraint.hpp`	Introduces `Constraint` as a `std::variant` wrapper (currently for `EquilibriumConstraint`).
`include/micm/constraint/constraint_set.hpp`	Stores constraints by value; computes residuals/Jacobian contributions for constraint rows.
`include/micm/constraint/equilibrium_constraint.hpp`	Refactors equilibrium constraint into a standalone concrete type (no longer inherits `Constraint`).
`include/micm/solver/solver_builder.hpp`	Adds `SetConstraints(...)` API and stores constraints in the builder.
`include/micm/solver/solver_builder.inl`	Builds `ConstraintSet`, merges constraint Jacobian sparsity, and passes constraints into solver policies.
`include/micm/solver/state.hpp`	Adds `number_of_constraints_`, `constraint_size_`, and `upper_left_identity_diagonal_` fields.
`include/micm/solver/state.inl`	Builds Jacobian sized `state_size_ + constraint_size_`; initializes identity-diagonal metadata.
`include/micm/solver/rosenbrock.hpp`	Threads `ConstraintSet` through Rosenbrock solver constructors.
`include/micm/solver/rosenbrock.inl`	Adds constraint forcing/Jacobian terms and modifies diagonal regularization behavior for DAE support.
`include/micm/solver/rosenbrock_temporary_variables.hpp`	Allocates Rosenbrock temporaries sized to species + constraint rows.
`include/micm/solver/backward_euler.hpp`	Adds `ConstraintSet` to constructor signature for API compatibility (not yet used).
`include/micm/solver/solver.hpp`	Removes `GetNumberOfSpecies()` / `GetNumberOfReactions()` accessors.
`test/integration/test_equilibrium.cpp`	New integration tests verifying `ConstraintSet` API and builder acceptance of constraints.
`test/integration/CMakeLists.txt`	Registers the new `equilibrium` integration test.
`test/unit/constraint/test_constraint_set.cpp`	Updates tests to use `std::vector<Constraint>` and `std::unordered_map`.
`test/unit/process/test_process_configuration.cpp`	Comment typo adjustment (still contains one remaining typo).
`test/unit/solver/test_rosenbrock.cpp`	Minor formatting fix.
`test/unit/solver/test__policy.hpp`	Adds `<iomanip>` and minor formatting fixes.

Comments suppressed due to low confidence (1)

include/micm/solver/solver.hpp:105

GetNumberOfSpecies() / GetNumberOfReactions() were removed from this public header. If this is part of the public API, this is a breaking change; consider keeping them (possibly delegating to state_parameters_) or providing a replacement accessor to avoid downstream breakage.

    StatePolicy GetState(const std::size_t number_of_grid_cells = 1) const
    {
      auto state = std::move(StatePolicy(state_parameters_, number_of_grid_cells));
      if constexpr (std::is_convertible_v<typename SolverPolicy::ParametersType, RosenbrockSolverParameters>)
      {

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include/micm/solver/rosenbrock.inl

Copilot · 2026-02-11T06:45:27Z

include/micm/solver/state.inl

    if constexpr (LuDecompositionInPlaceConcept<LuDecompositionPolicy, SparseMatrixPolicy>)
    {
      jacobian_ =
-          BuildJacobian<SparseMatrixPolicy>(parameters.nonzero_jacobian_elements_, number_of_grid_cells, state_size_, true);
+          BuildJacobian<SparseMatrixPolicy>(parameters.nonzero_jacobian_elements_, number_of_grid_cells, state_size_ + constraint_size_, true);
      auto lu = LuDecompositionPolicy::template GetLUMatrix<SparseMatrixPolicy>(jacobian_, 0, false);
      jacobian_ = std::move(lu);
    }
    else
    {
      jacobian_ =
-          BuildJacobian<SparseMatrixPolicy>(parameters.nonzero_jacobian_elements_, number_of_grid_cells, state_size_, false);
+          BuildJacobian<SparseMatrixPolicy>(parameters.nonzero_jacobian_elements_, number_of_grid_cells, state_size_ + constraint_size_, false);
      auto lu = LuDecompositionPolicy::template GetLUMatrices<SparseMatrixPolicy, LMatrixPolicy, UMatrixPolicy>(


jacobian_ is now built with size state_size_ + constraint_size_, but variables_ is still allocated from parameters.variable_names_.size() (species only). Several solver paths assume these dimensions match (e.g., linear solves over the Jacobian’s dimension), so enabling constraints risks out-of-bounds access/termination unless the state/temporary matrices are made dimension-consistent or solver code is updated to explicitly operate on the extended size.

@copilot open a new pull request to apply changes based on this feedback

include/micm/constraint/equilibrium_constraint.hpp

test/unit/process/test_process_configuration.cpp

include/micm/solver/rosenbrock.inl

include/micm/solver/solver_builder.inl

include/micm/constraint/constraint_set.hpp

include/micm/solver/rosenbrock.inl

Copilot · 2026-02-11T07:00:54Z

@boulderdaze I've opened a new pull request, #928, to work on those changes. Once the pull request is ready, I'll request review from you.

#928) * Initial plan * Add constraint Jacobian terms on rejected-step path Co-authored-by: boulderdaze <55209567+boulderdaze@users.noreply.github.com> * Fix comment: should say 'Subtract' not 'Add' for constraint Jacobian Co-authored-by: boulderdaze <55209567+boulderdaze@users.noreply.github.com> --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: boulderdaze <55209567+boulderdaze@users.noreply.github.com>

Copilot · 2026-02-11T07:30:42Z

@boulderdaze I've opened a new pull request, #929, to work on those changes. Once the pull request is ready, I'll request review from you.

…CAR/micm into v2-review-dae-3-rosenbrock-integration

dwfncar and others added 30 commits January 17, 2026 20:18

Rename forcing_jacobian_parallel.md for clarity

7f532f1

Rename to constraintset_mirrors_processset.md to better describe the document's purpose: showing how ConstraintSet mirrors ProcessSet's design for Jacobian computation. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Cleanup.

1f7ba7d

Added detailed Codex reviews and recommendations in TODO.

6a0ae29

Added Codex 5.2 at Extra High reasoning depth review pass.

0bb0a29

Merge branch 'main' into dae-1-constraint-classes

62c6af5

merge main

3623120

Merge branch 'dae-1-constraint-classes' into dae-3-rosenbrock-integra…

351cd5f

…tion

fix the tests

7798bab

constraint check is done out of loop

7c84ff8

remove unused function

2a127af

Review dae 1 constraint classes (#914)

59577b7

remove md files, and update the test names

fix the typo

0189d1c

add a missing header

f0c5b7f

Merge branch 'dae-1-constraint-classes' into dae-3-rosenbrock-integra…

7714eda

…tion

Merge branch 'dae-3-rosenbrock-integration' into v2-review-dae-3-rose…

e68744b

…nbrock-integration

remove unnecessary setter for constraints

c0d8d56

change the type of unique ptr to vector

b8cc902

remove unncessary docs

77ba699

boulderdaze added 8 commits February 10, 2026 00:35

fix test

5d98cfa

code clean up

e229bf9

revert the previous change for get solver

b66fca0

make builder copyable

b3cca64

fix test

119d567

add comments on test

eda8cb0

revert back

dd83fdd

state size

3533f31

boulderdaze requested a review from Copilot February 11, 2026 06:36

Copilot started reviewing on behalf of boulderdaze February 11, 2026 06:36 View session

Copilot AI reviewed Feb 11, 2026

View reviewed changes

code cleanup

e8c2668

Copilot AI mentioned this pull request Feb 11, 2026

Fix missing constraint Jacobian terms on Rosenbrock rejected-step path #928

Merged

boulderdaze and others added 3 commits February 11, 2026 00:11

address copilot review

9335b46

address copilot review

46d09f9

Copilot AI mentioned this pull request Feb 11, 2026

Fix dimension mismatch in Rosenbrock solver when constraints are present #929

Closed

boulderdaze changed the title ~~[Temp] V2 review dae 3 rosenbrock integration~~ [Temp] V2 Review DAE 3 Rosenbrock integration Feb 11, 2026

boulderdaze added 4 commits February 11, 2026 00:42

nvhpc error

d6c83a7

Merge branch 'v2-review-dae-3-rosenbrock-integration' of github.com:N…

21a9315

…CAR/micm into v2-review-dae-3-rosenbrock-integration

add params for constructor for cuda

4a899b3

fix a bug

edef9a8

boulderdaze mentioned this pull request Feb 11, 2026

Review DAE 3 Rosenbrock integration #915

Closed

dwfncar requested review from dwfncar February 19, 2026 21:25

boulderdaze closed this Feb 26, 2026

boulderdaze deleted the v2-review-dae-3-rosenbrock-integration branch March 19, 2026 20:58

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[Temp] V2 Review DAE 3 Rosenbrock integration#927

[Temp] V2 Review DAE 3 Rosenbrock integration#927
boulderdaze wants to merge 52 commits intomainfrom
v2-review-dae-3-rosenbrock-integration

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