Eigen::ThreadedSparseProduct< SparseMatrixType_ > Class Template Reference

#include <Eigen/src/SparseCore/ThreadedSparseProduct.h>

Detailed Description

template<typename SparseMatrixType_>
class Eigen::ThreadedSparseProduct< SparseMatrixType_ >

Cached, thread-parallel sparse matrix * dense vector product.

Designed for iterative solvers (CG, BiCGSTAB, GMRES, LSCG) that multiply many times by the same sparse matrix and, in the case of LSCG, by its adjoint. The constructor (or analyzePattern()) computes an nnz-balanced row partition once and reuses it across every apply()/applyAdjoint() call.

The forward direction (apply) always runs a dot-product-per-outer kernel, which is embarrassingly parallel (no write conflicts). For matrices whose native storage order doesn't match the forward direction (ColMajor for forward, or RowMajor for adjoint), a transposed mirror is built lazily on first use. The mirror doubles the memory footprint of the matrix but permits conflict-free parallel writes for both directions.

The matrix is held by const reference (no copy). Caller is responsible for keeping it alive across apply calls, and for invalidating the cache when the matrix changes:

• sparsity-pattern change: call analyzePattern()/compute() to rebuild the partition and drop the mirror.
• coefficient-only change (same pattern): call refreshValues() to drop the (now-stale) mirror; the next mirror-using direction will rebuild it lazily. Without this call, mirror-backed directions would read frozen coefficients from the cached copy.

Aliasing: apply()/applyAdjoint() do NOT insert temporaries on overlap between x and y; callers must use distinct storage (the kernel writes y[i] from a sum over x[inner[k]] reads, which would mis-compute if y aliases x). Asserted in debug builds.

Thread-safety: the const apply()/applyAdjoint()/applyAddTo()/applyAdjointAddTo() methods are safe to call concurrently on the same operator – the lazy mirror is published through an atomic with double-checked locking. The non-const methods (analyzePattern()/compute()/refreshValues()) and destruction are NOT; they mutate or free the cached mirror, so they must not overlap any in-flight apply() (the same rule as calling any method concurrently with the destructor).

Layout: x and y are taken as Ref<const DenseVector> / Ref<DenseVector>. Plain vectors and unit-inner-stride views (e.g. a column of a ColMajor matrix, an unaligned Map of a contiguous buffer) bind without copying; a strided const input is copy-evaluated by Ref; a strided mutable output triggers a Ref runtime error.

Template Parameters

SparseMatrixType

A compressed Eigen::SparseMatrix<Scalar, Order, StorageIndex>.

Public Member Functions
ThreadedSparseProduct &	analyzePattern (const SparseMatrixType &mat)
void	apply (const ConstVectorRef &x, MutableVectorRef y) const
	Overwriting forward apply: y = A * x.
void	applyAddTo (const ConstVectorRef &x, MutableVectorRef y, const Scalar &alpha) const
	Accumulating forward apply: y += alpha * A * x.
void	applyAdjoint (const ConstVectorRef &x, MutableVectorRef y) const
	Overwriting adjoint apply: y = A^H * x.
void	applyAdjointAddTo (const ConstVectorRef &x, MutableVectorRef y, const Scalar &alpha) const
	Accumulating adjoint apply: y += alpha * A^H * x.
bool	hasMirror () const
	True iff the lazy adjoint mirror has been materialized.
ThreadPool *	pool () const
	Returns the thread pool used by this operator.
ThreadedSparseProduct &	refreshValues ()

Member Function Documentation

analyzePattern()

template<typename SparseMatrixType_>

ThreadedSparseProduct & Eigen::ThreadedSparseProduct< SparseMatrixType_ >::analyzePattern ( const SparseMatrixType & mat )

inline

Bind to mat and (re)compute the partition. Drops any previously built adjoint mirror.

refreshValues()

template<typename SparseMatrixType_>

ThreadedSparseProduct & Eigen::ThreadedSparseProduct< SparseMatrixType_ >::refreshValues ( )

inline

Drops the cached adjoint mirror without recomputing the partition. Use after coefficient-only updates to the bound matrix so the next applyAdjoint() (or forward apply on a ColMajor A) rebuilds the mirror with the new values.

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The documentation for this class was generated from the following file:

• /builds/libeigen/eigen/Eigen/src/SparseCore/ThreadedSparseProduct.h