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Feature sparse linalg solvers - #2841

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antonwolfy merged 178 commits into
IntelPython:masterfrom
abagusetty:feature-sparse-linalg-solvers
Oct 5, 2026
Merged

antonwolfy merged 178 commits into
IntelPython:masterfrom
abagusetty:feature-sparse-linalg-solvers

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@abagusetty

@abagusetty abagusetty commented Apr 9, 2026 •

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Adds support for from dpnp.scipy.sparse.linalg import LinearOperator, cg, gmres, minres
Fixes: #2831

  • Have you provided a meaningful PR description?
  • Have you added a test, reproducer or referred to an issue with a reproducer?
  • Have you tested your changes locally for CPU and GPU devices?
  • Have you made sure that new changes do not introduce compiler warnings?
  • Have you checked performance impact of proposed changes?
  • Have you added documentation for your changes, if necessary?
  • Have you added your changes to the changelog?

abagusetty and others added 30 commits April 2, 2026 12:52
…oneMKL hooks

- _interface.py: add full operator algebra (.H, .T, +, *, **, neg),
  _AdjointLinearOperator, _TransposedLinearOperator, _SumLinearOperator,
  _ProductLinearOperator, _ScaledLinearOperator, _PowerLinearOperator,
  IdentityOperator, MatrixLinearOperator, _AdjointMatrixOperator,
  _CustomLinearOperator factory dispatch; extend aslinearoperator
  to handle dpnp sparse and dense arrays

- _iterative.py: add _make_system (dtype validation, preconditioner
  wiring, working dtype selection); add _make_fast_matvec CSR/oneMKL
  SpMV hook; fix GMRES Arnoldi inner product to single oneMKL BLAS
  gemv (dpnp.dot) instead of slow Python vdot loop; offload
  Hessenberg lstsq to numpy.linalg.lstsq (CPU, matches CuPy);
  fix SciPy host-fallback tol->rtol deprecation via _scipy_tol_kwarg;
  add preconditioner support to CG; keep MINRES as SciPy-backed stub

Refs: CuPy v14.0.1 cupyx/scipy/sparse/linalg/_interface.py,
      cupyx/scipy/sparse/linalg/_iterative.py"
…gmres, minres

Modeled after CuPy's cupyx_tests/scipy_tests/sparse_tests/test_linalg.py.
Covers:
  - LinearOperator: shape, dtype inference, matvec/rmatvec/matmat,
    subclassing, __matmul__, __call__, edge cases
  - aslinearoperator: dense array, duck-type, identity passthrough,
    rmatvec from dense, invalid inputs
  - cg: SPD convergence, scipy reference match, x0 warm start, b_ndim=2,
    callback, atol, LinearOperator path, invalid inputs,
    non-convergence info check
  - gmres: diag-dominant convergence, scipy reference match, restart
    variants, x0, b_ndim=2, callbacks, complex systems, atol,
    non-convergence info check, Hilbert-matrix stress test
  - minres: SPD, symmetric-indefinite, scipy reference, shift parameter,
    non-square guard, LinearOperator path, callback
  - Integration: parametric (n, dtype) cross-solver tests via LinearOperator
  - Import smoke tests: __all__ completeness
- Use dpnp.tests.helper: assert_dtype_allclose, generate_random_numpy_array,
  get_all_dtypes, get_float_complex_dtypes, has_support_aspect64
- Use dpnp.tests.third_party.cupy testing harness (with_requires, etc.)
- Use numpy.testing assert_allclose / assert_array_equal / assert_raises
- Use dpnp.asnumpy() instead of numpy.asarray()
- Use pytest parametrize ids matching existing test conventions
- Use is_scipy_available() helper from tests/helper.py
- Strict class-per-solver organisation matching TestCholesky / TestDet etc.
…or dtype

Two bugs fixed:
1. _init_dtype() was calling dpnp.zeros(n) which defaults to float64,
   so a float32 matvec would upcast and return float64, making the
   inferred dtype wrong.  Fix: use dpnp.zeros(n, dtype=dpnp.int8) as
   SciPy/CuPy do — any numeric matvec will promote int8 to its own dtype.
2. _CustomLinearOperator.__init__ called _init_dtype() even when an
   explicit dtype was already supplied, overwriting the caller's value.
   Fix: _init_dtype() now short-circuits when self.dtype is already set.
…ption handling

Align gemv.cpp with the conventions established in blas/gemm.cpp:

Headers added:
- ext/common.hpp         (dpctl_td_ns, consistent with other extensions)
- utils/memory_overlap.hpp   (MemoryOverlap guard on x vs y)
- utils/output_validation.hpp (CheckWritable + AmpleMemory on y)
- utils/type_utils.hpp       (validate_type_for_device<T> in impl)
- <sstream>                  (needed for stringstream error_msg)

Exception handling added in sparse_gemv_impl():
- try/catch(oneapi::mkl::exception) around all oneMKL sparse calls
- try/catch(sycl::exception) around all oneMKL sparse calls
- release_matrix_handle cleanup in the exception error path
- throw std::runtime_error with descriptive message on catch

Input validation added in sparse_gemv():
- ndim checks: x and y must be 1-D
- queues_are_compatible() across all 5 USM arrays
- MemoryOverlap()(x, y) aliasing guard
- CheckWritable::throw_if_not_writable(y)
- AmpleMemory::throw_if_not_ample(y, num_rows)
- keep_args_alive() at function exit (was missing, returning empty event)
… table

Modeled after blas/gemm.cpp (2-D table: value type x index type) and
blas/gemv.cpp (dispatch vector pattern with ContigFactory + init_dispatch_table).

Changes:
- Add sparse/types_matrix.hpp with SparseGemvTypePairSupportFactory<Tv, Ti>
  encoding the 4 supported combinations: {float32,float64} x {int32,int64}
- Rewrite sparse_gemv_impl() to take typeless char* pointers (matching
  the blas gemv_impl signature style) — type info flows through template
  params only, no runtime branching inside the impl
- Replace the 60-line if/else val_typenum/idx_typenum chain in sparse_gemv()
  with a 2-D dispatch table lookup (gemv_dispatch_table[val_id][idx_id])
- Rename init_sparse_gemv_dispatch_vector -> init_sparse_gemv_dispatch_table
  and implement it via init_dispatch_table<> from ext/common.hpp
- All validation guards and exception handling from prior commit are preserved
…se_gemv_dispatch_table

Follows the rename made in gemv.cpp when the dispatch mechanism was
changed from a 1-D vector to a 2-D table (value type x index type).
All other declarations (sparse_gemv signature, parameters) are unchanged.
The oneMKL 2025-2 sparse BLAS API deprecated the old 8-argument
set_csr_data(queue, handle, nrows, ncols, index_base, row_ptr, col_ind,
values, deps) overload in favour of a new signature that takes the
sparse matrix handle as `spmat` and adds an explicit `nnz` argument:

  set_csr_data(queue, spmat, nrows, ncols, nnz, index_base,
               row_ptr, col_ind, values, deps)

Fixes:
- Replace old set_csr_data call with the new nnz-aware signature
- Silences the resulting -Wunused-parameter warning on `nnz` (now used)
- No functional change; all other logic is unchanged
…tring

Line 477: `hasattr(A, "rmatmat\")` had a Markdown-escaped backslash
leaked into the Python source, causing an unterminated string literal.
Fixed to `hasattr(A, "rmatmat")`.
dpnp.ndarray blocks implicit NumPy conversion via __array__ to prevent
silent dtype=object arrays. All test assertions must use .asnumpy()
to materialize device arrays onto the host explicitly.

Also replaces numpy.asarray(x_dp) in _rel_residual helper.
…dation order

- _iterative.py: raise NotImplementedError for M != None *before* the
  _HOST_N_THRESHOLD SciPy fast-path in cg() and gmres(), so the contract
  is enforced regardless of system size (fixes test_cg_preconditioner_unsupported_raises,
  test_gmres_preconditioner_unsupported_raises).
- _iterative.py: validate callback_type and raise NotImplementedError for
  'pr_norm' *before* the _HOST_N_THRESHOLD branch in gmres(), so small-n
  systems also see the error (fixes test_gmres_callback_type_pr_norm_raises).
- _iterative.py: pass callback_type='legacy' to scipy.sparse.linalg.gmres
  when delegating on the fast path to suppress SciPy DeprecationWarning.
- test_scipy_sparse_linalg.py: add dtype=numpy.float64 to expected arange()
  calls in test_identity_operator and test_gmres_happy_breakdown so strict
  NumPy 2.0 dtype-equality checks pass (float64 result vs int64 expected).
- Replace .asnumpy() method calls with dpnp.asnumpy() module fn
  (asnumpy is not an ndarray method in dpnp; it is a top-level fn)
- Fix dpnp.any(x) ambiguous truth value in x0 zero-check; replace
  with explicit `x0 is not None` guard for r0 initialisation
- Fix V_mat.T.conj() -> dpnp.conj(V_mat.T) in GMRES Arnoldi step
- Guard minres beta sqrt against tiny negative floats: sqrt(abs(...))
- Unify GMRES Hessenberg h_np assignment to avoid .real stripping
  producing wrong dtype for complex systems
- Fix float() cast on dpnp scalar norm inside GMRES inner h_j1 line
…failures)

The committed code used hypot(gbar, oldb) as delta_k which is the
gamma (norm) from the PREVIOUS rotation step, not the correct diagonal
entry from applying the previous Givens rotation to the current column.

The correct Paige-Saunders (1975) two-rotation recurrence is:

  oldeps = epsln
  delta  = cs * dbar + sn * alpha   # apply previous rotation
  gbar_k = sn * dbar - cs * alpha   # residual -> new rotation input
  epsln  = sn * beta
  dbar   = -cs * beta

  gamma = hypot(gbar_k, beta)       # NEW rotation eliminates beta
  cs    = gbar_k / gamma
  sn    = beta   / gamma

  w_new = (v - oldeps*w - delta*w2) / gamma  # three-term update

This matches scipy.sparse.linalg.minres and Choi (2006) eq. 6.11.

The buggy recurrence produced solutions ~1.08x away from the true
solution (rel_err ~1e0) instead of the expected ~1e-13.

Co-authored-by: fix-minres-recurrence
abagusetty and others added 5 commits August 28, 2026 09:55
Reading usm_ndarray data pointers after py::gil_scoped_release aborted the interpreter, since get_data() calls into the Python C-API; read both pointers before releasing the GIL, matching in_place.tpp.
Comment thread dpnp/tests/test_scipy_sparse_linalg.py Outdated
Comment thread dpnp/scipy/sparse/linalg/_interface.py
abagusetty and others added 2 commits August 30, 2026 20:48
Comment thread dpnp/backend/extensions/sparse/gemv.cpp
Comment thread dpnp/scipy/sparse/_csr.py Outdated
Comment thread dpnp/scipy/sparse/linalg/_iterative.py Outdated
Comment thread dpnp/scipy/sparse/linalg/_iterative.py
Comment thread dpnp/scipy/sparse/linalg/_interface.py
Comment thread dpnp/scipy/sparse/linalg/_iterative.py Outdated
Comment thread dpnp/scipy/sparse/linalg/_interface.py Outdated
…e bug

A prior commit accidentally deleted the entire rmatvec/rmatmat/adjoint/
transpose subsystem from _interface.py while addressing unrelated review
comments. Restore it, keeping the two comments that did target this file:

- LinearOperator.__init__: validate _isshape(shape) before int()
  truncation, so non-integer shapes like (3.7, 3.2) raise instead of
  silently rounding.
- MatrixLinearOperator._matvec: unify sparse/dense branches to
  self.A.dot(x), since dpnp.ndarray.dot already dispatches to gemv.

Also fix _ScaledLinearOperator: alpha_dtype used type(alpha) for plain
Python scalars, forcing strong dtype promotion (float64/complex128)
even when the operator was float32/complex64. This crashed
LinearOperator.__init__'s dpnp.empty(dtype=float64) probe on fp64-less
devices (e.g. Iris Xe). Promote weakly from the scalar value instead,
matching array-API semantics.

Verified: dpnp/tests/test_scipy_sparse_linalg.py 393 passed, on both
the default device and ONEAPI_DEVICE_SELECTOR=opencl:cpu.
Comment thread dpnp/tests/test_scipy_sparse_linalg.py Outdated
Comment thread dpnp/scipy/sparse/linalg/_interface.py Outdated
Comment thread dpnp/scipy/sparse/linalg/_iterative.py Outdated
Comment thread dpnp/scipy/sparse/linalg/_iterative.py
Comment thread dpnp/scipy/sparse/linalg/_interface.py Outdated
antonwolfy and others added 3 commits October 1, 2026 15:19
Co-authored-by: Anton <100830759+antonwolfy@users.noreply.github.com>
- clang-format: rewrap mkl_sparse::spmv calls in sparse/gemv.cpp
- gersemi: reformat execute_process COMMAND block in CMakeLists.txt
- pylint R0904: disable too-many-public-methods on csr_matrix
- pylint C0301: wrap 81-char comment in gmres
Comment thread dpnp/scipy/sparse/_csr.py
Comment thread dpnp/backend/extensions/sparse/gemv.hpp Outdated
Comment thread dpnp/backend/extensions/sparse/gemv.cpp Outdated
Comment thread dpnp/backend/extensions/sparse/gemv.cpp
Comment thread dpnp/tests/third_party/cupyx/scipy_tests/sparse_tests/test_linalg.py Outdated
antonwolfy and others added 9 commits October 1, 2026 19:21
The Conda package workflow builds with rattler-build using
conda-recipe/rattler_recipe.yaml, which was missing the
onemkl-sycl-sparse run dependency (present only in
conda-recipe/meta.yaml). Without it libmkl_sycl_sparse.so.6 is
absent at runtime and importing the sparse SpMV extension fails.
- dense path: allocate nnz==0 arrays and indptr via *_like(dense) so
  usm_type and queue follow the (possibly moved) input
- sort_indices: build row ids with the indices' usm_type, so indexing
  no longer promotes data/indices to "device"
- toarray: allocate the result like self._data
- fix comments claiming placement kwargs are no-ops for device input
third_party/cupyx/.../sparse_tests/test_linalg.py:
- drop non-upstream TestLinearOperatorSmoke (covered by own-scope tests)
- restore upstream M/N grid [1, 6]/[1, 7] and FutureWarning filters
- wrap the scipy side in aslinearoperator too for use_linear_operator
- use plain with_requires("scipy") and upstream gmres matrix setup
- skip float64/complex128 (not 8-byte dtypes) on fp64-less devices
- add from __future__ import annotations; drop stale notes

test_scipy_sparse_linalg.py:
- use the device default float type in tests hardcoding float64
- black formatting

gemv.cpp: clang-format indent fix
numpy.float64(2.0) * op raised on devices without fp64: the scalar's
float64 dtype made the scaled operator float64, which LinearOperator
rejects. Map a numpy scalar's dtype to the default device, as dpnp
elementwise ops do, so the declared dtype matches matvec's result.
The test now also checks that dtype match.

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Thanks @abagusetty for the great work and for patiently addressing all the review feedback, LGTM!

To get the PR ready for the release I pushed a few follow-up commits directly to the branch:

  • fixed pre-commit failures (clang-format, gersemi, pylint)
  • added the missing onemkl-sycl-sparse run dependency to conda-recipe/rattler_recipe.yaml
  • shortened the alpha/beta and placeholder comments in sparse/gemv.cpp
  • csr_matrix now preserves the requested usm_type in the dense constructor path, sort_indices() and toarray()
  • aligned third_party/cupyx/.../sparse_tests/test_linalg.py with upstream CuPy (dropped the non-upstream class, restored the size-1 M/N cases and the FutureWarning filters, wrapped the SciPy side in aslinearoperator) and fixed tests failing on devices without fp64
  • _ScaledLinearOperator maps a NumPy scalar's dtype to the device, so e.g. numpy.float64(2.0) * op no longer raises on devices without fp64

The CI failures are unrelated to this PR.

@abagusetty

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Thanks @antonwolfy @vlad-perevezentsev for pushing this. Really helps the with the app, we are working with. Many months of effort taking into shape. Appreciate for the patience with this PR!

@antonwolfy
antonwolfy merged commit 7063a51 into IntelPython:master Oct 5, 2026
111 of 113 checks passed
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Request support for scipy.sparse.linalg LinearOperator, GMRES, and MINRES

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