cblas_?trmv

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_?trmv

Computes a matrix-vector product using a triangular matrix.

Syntax

void cblas_strmv (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const CBLAS_TRANSPOSE trans, const CBLAS_DIAG diag, const MKL_INT n, const float *a, const MKL_INT lda, float *x, const MKL_INT incx);

void cblas_dtrmv (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const CBLAS_TRANSPOSE trans, const CBLAS_DIAG diag, const MKL_INT n, const double *a, const MKL_INT lda, double *x, const MKL_INT incx);

void cblas_ctrmv (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const CBLAS_TRANSPOSE trans, const CBLAS_DIAG diag, const MKL_INT n, const void *a, const MKL_INT lda, void *x, const MKL_INT incx);

void cblas_ztrmv (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const CBLAS_TRANSPOSE trans, const CBLAS_DIAG diag, const MKL_INT n, const void *a, const MKL_INT lda, void *x, const MKL_INT incx);

Include Files

mkl.h

Description

The ?trmv routines perform one of the following matrix-vector operations defined as

x := A*x, or x := A'*x, or x := conjg(A')*x,

where:

x is an n-element vector,

A is an n-by-n unit, or non-unit, upper or lower triangular matrix.

Input Parameters

Layout

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

uplo

Specifies whether the matrix A is upper or lower triangular:

uplo = CblasUpper

if uplo = CblasLower, then the matrix is low triangular.

trans

Specifies the operation:

if trans=CblasNoTrans, then x := A*x;

if trans=CblasTrans, then x := A'*x;

if trans=CblasConjTrans, then x := conjg(A')*x.

diag

Specifies whether the matrix A is unit triangular:

if diag = CblasUnit then the matrix is unit triangular;

if diag = CblasNonUnit , then the matrix is not unit triangular.

n

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

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 matrix 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 matrix and the strictly upper triangular part of a is not referenced.

When diag = CblasUnit, the diagonal elements of a are not referenced either, but are assumed to be unity.

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.

Output Parameters

x: Overwritten with the transformed vector x.

Parent topic: BLAS Level 2 Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

cblas_?trmv