spr

Performs a rank-1 update of a symmetric packed matrix.

Syntax

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

spr supports the following precisions and devices.

T

Devices Supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

Description

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

A <- alpha*x*xT + A

where:

alpha is scalar,

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

x is a vector 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.

a

Buffer holding input matrix A. Must have size at least (n*(n-n))/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.