Expose ILU0 numeric boost configuration for CUDA and HIP

[kakeueda]

Description

The numeric boost tolerance and value in the CUDA ILU0 solver are hard-coded to 1e-6. This PR makes them configurable through the existing setCliParam() interface.

To see the effect of these values I tested the solver with FIDAP012 from the NIST Matrix Market, a nonsymmetric linear system arising from a fluid dynamics problem

./build/examples/sysGmres.exe \
  -m ~/tmp/matrixmarket/fidap012.mtx \
  -r ~/tmp/matrixmarket/fidap012_rhs1.mtx \
  -b cuda \
  -i fgmres

The number of iterations changed as follows:

Boost value	Number of FGMRES iterations	Final relative residual
1e-6	1121	9.9392e-13
1e-7	143	9.2850e-13
1e-8	143	9.2850e-13

Some problems are sensitive to this value.

Proposed changes

• Added a zero_diagonal parameter to the CPU ILU0 solver through the existing setCliParam() interface.
• Added boost_tolerance and boost_value parameters to the CUDA/HIP ILU0 solvers through the existing setCliParam() interface.
• Added SystemSolver::getPreconditionerSolver() so users can configure ILU0 numerical stabilization parameters through SystemSolver.
• Updated testSysGmres and MatrixFactorizationTests to configure ILU0 parameters.
• Fixed misplaced entries in CHANGELOG.md.

Checklist

• All tests pass (make test and make test_install per testing instructions). Code tested on
  • CPU backend
  • CUDA backend
  • HIP backend
• I have manually run the non-experimental examples and verified that residuals are close to machine precision. (In your build directory run: ./examples/<your_example>.exe -h to get instructions how to run examples). Code tested on:
  • CPU backend
  • CUDA backend
  • HIP backend
• Code compiles cleanly with flags -Wall -Wpedantic -Wconversion -Wextra.
• The new code follows Re::Solve style guidelines.
• [N/A] There are unit tests for the new code.
• The new code is documented.
• [N/A] The feature branch is rebased with respect to the target branch.
• I have updated CHANGELOG.md to reflect the changes in this PR. If this is a minor PR that is part of a larger fix already included in the file, state so.

[kakeueda]

I’d appreciate any help with HIP testing

[tamar-dewilde]

Tested on HIP. All 64 tests and install validation passed.

[tamar-dewilde]

The PR description says this getter lets users configure the numeric boost through SystemSolver. How should users call setZeroDiagonal() through it? The getter returns LinSolverDirect&, which does not declare that method, so the direct call does not compile.

I could only call the setter by including LinSolverDirectCuSparseILU0.hpp and casting the returned solver to that concrete type. Is that the intended use, or should LinSolverDirect provide a common way to access this setting? LinSolverDirectCpuILU0 already has the same setter.

[kakeueda]

Thank you for pointing this out! I added the BOOST_TOLERANCE and BOOST_VALUE parameter IDs and the corresponding cli param settings so users can now configure the numeric boost through SystemSolver rather than casting it to a concrete type.

I also implemented numeric boost support for HIP since it was needed for the configuration test added to testSysGmres.cpp.

Can you test this again on HIP?

[kakeueda]

One remaining inconsistency is that CPU ILU0 still uses zero_diagonal for both the zero-pivot threshold and replacement value. Separating them also requires changing CPU ILU0’s numerical behavior. I left it out of this PR.