spmv

Computes a matrix-vector product with a symmetric packed matrix.

Syntax

void spmv(queue &exec_queue, uplo upper_lower, std::int64_t n, T alpha, buffer<T, 1> &a, buffer<T, 1> &x, std::int64_t incx, T beta, buffer<T, 1> &y, std::int64_t incy)

spmv supports the following precisions and devices.

T

Devices Supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

Description

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

y <- alpha*A*x + beta*y

where:

alpha and beta are scalars,

A is an n-by-n symmetric matrix, supplied in packed form.

x and y are vectors of length n.

Input Parameters

exec_queue

The queue where the routine should be executed.

upper_lower

Specifies whether A is upper or lower triangular. See Data Types for more details.

n

Number of rows and columns of A. Must be at least zero.

alpha

Scaling factor for the matrix-vector product.

a

Buffer holding input matrix A. Must have size at least (n*(n+1))/2. See Matrix and Vector Storage for more details.

x

Buffer holding input vector x. The buffer must be of size at least (1 + (n - 1)*abs(incx)). See Matrix and Vector Storage for more details.

incx

Stride of vector x.

beta

Scaling factor for vector y.

y

Buffer holding input/output vector y. The buffer must be of size at least (1 + (n - 1)*abs(incy)). See Matrix and Vector Storage for more details.

incy

Stride of vector y.

Output Parameters

y

Buffer holding the updated vector y.