p?gemv

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 12/16/2022

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p?gemv

Computes a distributed matrix-vector product using a general matrix.

Syntax

void psgemv (const char *trans , const MKL_INT *m , const MKL_INT *n , const float *alpha , const float *a , const MKL_INT *ia , const MKL_INT *ja , const MKL_INT *desca , const float *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx , const float *beta , float *y , const MKL_INT *iy , const MKL_INT *jy , const MKL_INT *descy , const MKL_INT *incy );

void pdgemv (const char *trans , const MKL_INT *m , const MKL_INT *n , const double *alpha , const double *a , const MKL_INT *ia , const MKL_INT *ja , const MKL_INT *desca , const double *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx , const double *beta , double *y , const MKL_INT *iy , const MKL_INT *jy , const MKL_INT *descy , const MKL_INT *incy );

void pcgemv (const char *trans , const MKL_INT *m , const MKL_INT *n , const MKL_Complex8 *alpha , const MKL_Complex8 *a , const MKL_INT *ia , const MKL_INT *ja , const MKL_INT *desca , const MKL_Complex8 *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx , const MKL_Complex8 *beta , MKL_Complex8 *y , const MKL_INT *iy , const MKL_INT *jy , const MKL_INT *descy , const MKL_INT *incy );

void pzgemv (const char *trans , const MKL_INT *m , const MKL_INT *n , const MKL_Complex16 *alpha , const MKL_Complex16 *a , const MKL_INT *ia , const MKL_INT *ja , const MKL_INT *desca , const MKL_Complex16 *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx , const MKL_Complex16 *beta , MKL_Complex16 *y , const MKL_INT *iy , const MKL_INT *jy , const MKL_INT *descy , const MKL_INT *incy );

Include Files

mkl_pblas.h

Description

The p?gemv routines perform a distributed matrix-vector operation defined as

sub(y)  := alpha*sub(A)*sub(x) + beta*sub(y),

sub(y)  := alpha*sub(A)'*sub(x) + beta*sub(y),

sub(y)  := alpha*conjg(sub(A)')*sub(x) + beta*sub(y),

where

alpha and beta are scalars,

sub(A) is a m-by-n submatrix, sub(A) = A(ia:ia+m-1, ja:ja+n-1),

sub(x) and sub(y) are subvectors.

When trans = 'N' or 'n', sub(x) denotes X(ix, jx:jx+n-1) if incx = m_x, and X(ix: ix+n-1, jx) if incx = 1,sub(y) denotes Y(iy, jy:jy+m-1) if incy = m_y, and Y(iy: iy+m-1, jy) if incy = 1.

When trans = 'T' or 't', or 'C', or 'c', sub(x) denotes X(ix, jx:jx+m-1) if incx = m_x, and X(ix: ix+m-1, jx) if incx = 1,sub(y) denotes Y(iy, jy:jy+n-1) if incy = m_y, and Y(iy: iy+m-1, jy) if incy = 1.

Input Parameters

trans

(global) Specifies the operation:

if trans= 'N' or 'n', then sub(y) := alpha*sub(A)'*sub(x) + beta*sub(y);

if trans= 'T' or 't', then sub(y) := alpha*sub(A)'*sub(x) + beta*sub(y);

if trans= 'C' or 'c', then sub(y) := alpha*conjg(subA)')*sub(x) + beta*sub(y).

m

(global) Specifies the number of rows of the distributed matrix sub(A), m≥0.

n

(global) Specifies the number of columns of the distributed matrix sub(A), n≥0.

alpha

(global)

Specifies the scalar alpha.

a

(local)

Array, size (lld_a, LOCq(ja+n-1)). Before entry this array must contain the local pieces of the distributed matrix sub(A).

ia, ja

(global) The row and column indices in the distributed matrix A indicating the first row and the first column of the submatrix sub(A), respectively.

desca

(global and local) array of dimension 9. The array descriptor of the distributed matrix A.

x

(local)

Array, size (jx-1)*m_x + ix+(n-1)*abs(incx)) when trans = 'N' or 'n', and (jx-1)*m_x + ix+(m-1)*abs(incx)) otherwise.

This array contains the entries of the distributed vector sub(x).

ix, jx

(global) The row and column indices in the distributed matrix X indicating the first row and the first column of the submatrix sub(x), respectively.

descx

(global and local) array of dimension 9. The array descriptor of the distributed matrix X.

incx

(global) Specifies the increment for the elements of sub(x). Only two values are supported, namely 1 and m_x. incx must not be zero.

beta

(global)

Specifies the scalar beta. When beta is set to zero, then sub(y) need not be set on input.

y

(local)

Array, size (jy-1)*m_y + iy+(m-1)*abs(incy)) when trans = 'N' or 'n', and (jy-1)*m_y + iy+(n-1)*abs(incy)) otherwise.

This array contains the entries of the distributed vector sub(y).

iy, jy

(global) The row and column indices in the distributed matrix Y indicating the first row and the first column of the submatrix sub(y), respectively.

descy

(global and local) array of dimension 9. The array descriptor of the distributed matrix Y.

incy

(global) Specifies the increment for the elements of sub(y). Only two values are supported, namely 1 and m_y. incy must not be zero.

Output Parameters

y: Overwritten by the updated distributed vector sub(y).

Parent topic: PBLAS Level 2 Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

p?gemv