cblas_?symv

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 3/31/2023

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cblas_?symv

Computes a matrix-vector product for a symmetric matrix.

Syntax

void cblas_ssymv (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const MKL_INT n, const float alpha, const float *a, const MKL_INT lda, const float *x, const MKL_INT incx, const float beta, float *y, const MKL_INT incy);

void cblas_dsymv (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const MKL_INT n, const double alpha, const double *a, const MKL_INT lda, const double *x, const MKL_INT incx, const double beta, double *y, const MKL_INT incy);

Include Files

mkl.h

Description

The ?symv routines perform a matrix-vector operation defined as

y := alpha*A*x + beta*y,

where:

alpha and beta are scalars,

x and y are n-element vectors,

A is an n-by-n symmetric matrix.

Input Parameters

Layout

Specifies whether two-dimensional array storage is row-major (CblasRowMajor) or column-major (CblasColMajor).

uplo

Specifies whether the upper or lower triangular part of the array a is used.

If uplo = CblasUpper, then the upper triangular part of the array a is used.

If uplo = CblasLower, then the low triangular part of the array a is used.

n

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

alpha

Specifies the scalar alpha.

a

Array, size lda*n.

Before entry with uplo = CblasUpper, the leading n-by-n upper triangular part of the array a must contain the upper triangular part of the symmetric matrix A and the strictly lower triangular part of a is not referenced. Before entry with uplo = CblasLower, the leading n-by-n lower triangular part of the array a must contain the lower triangular part of the symmetric matrix A and the strictly upper triangular part of a is not referenced.

lda

Specifies the leading dimension of a as declared in the calling (sub)program. The value of lda must be at least max(1, n).

x

Array, size at least (1 + (n - 1)*abs(incx)). Before entry, the incremented array x must contain the n-element vector x.

incx

Specifies the increment for the elements of x.

The value of incx must not be zero.

beta

Specifies the scalar beta.

When beta is supplied as zero, then y need not be set on input.

y

Array, size at least (1 + (n - 1)*abs(incy)). Before entry, the incremented array y must contain the n-element vector y.

incy

Specifies the increment for the elements of y.

The value of incy must not be zero.

Output Parameters

y: Overwritten by the updated vector y.

Parent topic: BLAS Level 2 Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

cblas_?symv