spr2

Computes a rank-2 update of a symmetric packed matrix.

Syntax

void spr2(queue &exec_queue, uplo upper_lower, std::int64_t n, T alpha, buffer<T, 1> &x, std::int64_t incx, buffer<T, 1> &y, std::int64_t incy, buffer<T, 1> &a)

spr2 supports the following precisions and devices.

T

Devices Supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

Description

The spr2 routines compute two scalar-vector-vector products and add them to a symmetric packed matrix. The operation is defined as

A <- alpha*x*yT + alpha*y*xT + A

where:

alpha is scalar,

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.

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.

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.

a

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

Output Parameters

sycl:

a

Buffer holding the updated upper triangularpart of the symmetric matrix A if upper_lower =upper or the updated lower triangular part of thesymmetric matrix A if upper_lower =lower.

spr (USM Version) spr2 (USM Version)