gemv (USM Version)

Computes a matrix-vector product using a general matrix.

Syntax

event gemv(queue &exec_queue, transpose trans, std::int64_t m, std::int64_t n, T alpha, const T *a, std::int64_t lda, const T *x, std::int64_t incx, T beta, T *y, std::int64_t incy, const vector_class<event> &dependencies = {})

The USM version of gemv supports the following precisions and devices.

T

Devices Supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

std::complex<float>

Host, CPU, and GPU

std::complex<double>

Host, CPU, and GPU

Description

The gemv routines compute a scalar-matrix-vector product and add the result to a scalar-vector product, with a general matrix. The operation is defined as

y  <- alpha*op(A)*x + beta*y

where:

op(A) is one of op(A) = A, or op(A) = AT, or op(A) = AH,

alpha and beta are scalars,

A is an m-by-n matrix, and x, y are vectors.

Input Parameters

exec_queue

The queue where the routine should be executed.

trans

Specifies op(A), the transposition operation applied to A. See Data Types for more details.

m

Specifies the number of rows of the matrix A. The value of m must be at least zero.

n

Specifies the number of columns of the matrix A. The value of n must be at least zero.

alpha

Scaling factor for the matrix-vector product.

a

The array holding input matrix A must have size at least lda*n if column major layout is used, or at least lda*m if row major layout is used.

lda

The leading dimension of matrix A. It must be positive and at least m if column major layout is used or at least n if row major layout is used.

x

Pointer to the input vector x. The length len of vector x is n if A is not transposed, and m if A is transposed. The array holding vector x must be of size at least (1 + (len - 1)*abs(incx)). See Matrix and Vector Storage for more details.

incx

The stride of vector x.

beta

The scaling factor for vector y.

y

Pointer to input/output vector y. The length len of vector y is m, if A is not transposed, and n if A is transposed. The array holding input/output vector y must be of size at least (1 + (len - 1)*abs(incy)) where len is this length. See Matrix and Vector Storage for more details.

incy

The stride of vector y.

dependencies

List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.

Output Parameters

y

The pointer to updated vector y.

Example

An example of how to use gemvcan be found in the Intel® oneMKL installation directory, under:

examples/sycl/blas/gemv.cpp

Return Values

Output event to wait on to ensure computation is complete.