oneapi::mkl::sparse::symv#

Computes a sparse matrix-dense vector product for a symmetric matrix built from the lower or upper triangular of the input matrix.

Description#

Note

Refer to Sparse BLAS Supported Data and Integer Types for a list of supported <DATA_TYPE> and <INT_TYPE> data and integer types and refer to Error Handling for a detailed description of the possible exceptions thrown.

The oneapi::mkl::sparse::symv routine computes a sparse symmetric matrix-dense vector product for a real symmetric matrix built from the lower or upper triangular portion of the input matrix \(A\) defined as

\[y \leftarrow \alpha\cdot \text{sym}(A)\cdot x + \beta \cdot y\]

where \(\alpha\) and \(\beta\) are scalars, \(A\) is a real-valued square sparse matrix of dimension \(m\) rows and columns, \(\text{sym}()\) is a matrix modifier which symmetrizes the matrix according to the oneapi::mkl::uplo value and \(x\) and \(y\) are dense vectors.

For a given matrix decomposition into lower, diagonal and upper parts \(A = L+D+U\), the symv routine with oneapi::mkl::uplo::lower selected will perform the matrix product with \(\text{sym}(A) = L+D+L^T\) and for oneapi::mkl::uplo::upper will perform the matrix product using \(\text{sym}(A) = U^T+D+U\).

API#

Syntax#

Using SYCL buffers:

namespace oneapi::mkl::sparse {
    void symv (
        sycl::queue &queue,
        oneapi::mkl::uplo uplo_val,
        const DATA_TYPE alpha,
        oneapi::mkl::sparse::matrix_handle_t A,
        sycl::buffer<DATA_TYPE, 1> &x,
        const DATA_TYPE beta,
        sycl::buffer<DATA_TYPE, 1> &y)
}

Using USM pointers:

namespace oneapi::mkl::sparse {
    sycl::event symv (
        sycl::queue &queue,
        oneapi::mkl::uplo uplo_val,
        const DATA_TYPE alpha,
        oneapi::mkl::sparse::matrix_handle_t A,
        const DATA_TYPE *x,
        const DATA_TYPE beta,
        DATA_TYPE *y,
        const std::vector<sycl::event> &dependencies = {})
}

Include Files#

  • oneapi/mkl/spblas.hpp

Input Parameters#

queue

Specifies the SYCL command queue which will be used for SYCL kernels execution.

uplo_val

Specifies which part is to be processed.

oneapi::mkl::uplo::lower

The lower part is used for symmetric product.

oneapi::mkl::uplo::upper

The upper part is used for symmetric product.

alpha

Specifies the scalar, \(\alpha\).

A

Handle to object containing sparse matrix and other internal data. Created using one of the oneapi::mkl::sparse::set_<sparse_matrix_type>_data routines.

Note

Currently, the only supported case for <sparse_matrix_type> is csr.

x

SYCL buffer or device-accessible USM pointer of size at least equal to the number of columns, \(m\), of input matrix.

beta

Specifies the scalar, \(\beta\).

y

SYCL buffer or device-accessible USM pointer of size at least equal to the number of rows, \(m\), of the input matrix.

dependencies

A vector of type std::vector<sycl::event> containing the list of events that the oneapi::mkl::sparse::symv routine depends on.

Output Parameters#

y

Overwritten by the updated vector \(y\).

Return Values (USM Only)#

sycl::event

SYCL event which can be waited upon or added as a dependency for the completion of the symv routine.

Examples#

An example of how to use oneapi::mkl::sparse::symv with SYCL buffers can be found in the oneMKL installation directory, under:

share/doc/mkl/examples/sycl/sparse_blas/source/csr_symv.cpp