p?hemm

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 12/16/2022

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p?hemm

Performs a scalar-matrix-matrix product (one matrix operand is Hermitian) and adds the result to a scalar-matrix product.

Syntax

call pchemm(side, uplo, m, n, alpha, a, ia, ja, desca, b, ib, jb, descb, beta, c, ic, jc, descc)

call pzhemm(side, uplo, m, n, alpha, a, ia, ja, desca, b, ib, jb, descb, beta, c, ic, jc, descc)

Include Files

mkl_pblas.h

Description

The p?hemm routines perform a matrix-matrix operation with distributed matrices. The operation is defined as

sub(C):=alpha*sub(A)*sub(B)+ beta*sub(C),

sub(C):=alpha*sub(B)*sub(A)+ beta*sub(C),

where:

alpha and beta are scalars,

sub(A) is a Hermitian distributed matrix, sub(A)=A(ia:ia+m-1, ja:ja+m-1), if side = 'L', and sub(A)=A(ia:ia+n-1, ja:ja+n-1), if side = 'R'.

sub(B) and sub(C) are m-by-n distributed matrices.

sub(B)=B(ib:ib+m-1, jb:jb+n-1), sub(C)=C(ic:ic+m-1, jc:jc+n-1).

Input Parameters

side

(global) CHARACTER*1. Specifies whether the Hermitian distributed matrix sub(A) appears on the left or right in the operation:

if side = 'L' or 'l', then sub(C) := alpha*sub(A) *sub(B) + beta*sub(C);

if side = 'R' or 'r', then sub(C) := alpha*sub(B) *sub(A) + beta*sub(C).

uplo

(global) CHARACTER*1. Specifies whether the upper or lower triangular part of the Hermitian distributed matrix sub(A) is used:

if uplo = 'U' or 'u', then the upper triangular part is used;

if uplo = 'L' or 'l', then the lower triangular part is used.

m

(global) INTEGER. Specifies the number of rows of the distribute submatrix sub(C), m≥ 0.

n

(global) INTEGER. Specifies the number of columns of the distribute submatrix sub(C), n≥ 0.

alpha

(global)COMPLEX for pchemm

DOUBLE COMPLEX for pzhemm

Specifies the scalar alpha.

a

(local)COMPLEX for pchemm

DOUBLE COMPLEX for pzhemm

Array, size (lld_a, LOCq(ja+na-1)).

Before entry this array must contain the local pieces of the symmetric distributed matrix sub(A), such that when uplo = 'U' or 'u', the na-by-na upper triangular part of the distributed matrix sub(A) must contain the upper triangular part of the Hermitian distributed matrix and the strictly lower triangular part of sub(A) is not referenced, and when uplo = 'L' or 'l', the na-by-na lower triangular part of the distributed matrix sub(A) must contain the lower triangular part of the Hermitian distributed matrix and the strictly upper triangular part of sub(A) is not referenced.

ia, ja

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

b

(local)COMPLEX for pchemm

DOUBLE COMPLEX for pzhemm

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

ib, jb

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

descb

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

beta

(global)COMPLEX for pchemm

DOUBLE COMPLEX for pzhemm

Specifies the scalar beta.

When beta is set to zero, then sub(C) need not be set on input.

c

(local)COMPLEX for pchemm

DOUBLE COMPLEX for pzhemm

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

ic, jc

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

descc

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

Output Parameters

c: Overwritten by the m-by-n updated distributed matrix.

Parent topic: PBLAS Level 3 Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

p?hemm