C Library Functions - ssymm (3)

NAME

ssymm(3f) - [BLAS:SINGLE_BLAS_LEVEL3] C:=alpha*A*B+beta*C, A symmetric, B, C rectangular.

Synopsis
Definition
Options
C
Authors
Further Details
See Also

SYNOPSIS

subroutine ssymm(side,uplo,m,n,alpha,a,lda,b,ldb,beta,c,ldc)

      .. Scalar Arguments ..
      real,intent(in)      :: alpha,beta
      integer,intent(in)   :: lda,ldb,ldc,m,n
      character,intent(in) :: side,uplo
      ..
      .. Array Arguments ..
      real,intent(in)      :: a(lda,*),b(ldb,*)
      real,intent(inout)   :: c(ldc,*)
      ..

DEFINITION

SSYMM performs one of the matrix-matrix operations
    C := alpha*A*B + beta*C,
or
    C := alpha*B*A + beta*C,
where alpha and beta are scalars, A is a symmetric matrix and B and C are m by n matrices.

OPTIONS

SIDE

SIDE is CHARACTER*1 On entry, SIDE specifies whether the symmetric matrix A appears on the left or right in the operation as follows:
              SIDE = ’L’ or ’l’   C := alpha*A*B + beta*C,

              SIDE = ’R’ or ’r’   C := alpha*B*A + beta*C,

UPLO

UPLO is CHARACTER*1 On entry, UPLO specifies whether the upper or lower triangular part of the symmetric matrix A is to be referenced as follows:

UPLO = ’U’ or ’u’ Only the upper triangular part of the symmetric matrix is to be referenced.

UPLO = ’L’ or ’l’ Only the lower triangular part of the symmetric matrix is to be referenced.

M

M is INTEGER On entry, M specifies the number of rows of the matrix C. M must be at least zero.

N

N is INTEGER On entry, N specifies the number of columns of the matrix C. N must be at least zero.

ALPHA

ALPHA is REAL On entry, ALPHA specifies the scalar alpha.

A

A is REAL array, dimension ( LDA, ka ), where ka is m when SIDE = ’L’ or ’l’ and is n otherwise. Before entry with SIDE = ’L’ or ’l’, the m by m part of the array A must contain the symmetric matrix, such that when UPLO = ’U’ or ’u’, the leading m by m upper triangular part of the array A must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of A is not referenced, and when UPLO = ’L’ or ’l’, the leading m by m lower triangular part of the array A must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of A is not referenced. Before entry with SIDE = ’R’ or ’r’, the n by n part of the array A must contain the symmetric matrix, such that when UPLO = ’U’ or ’u’, the leading n by n upper triangular part of the array A must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of A is not referenced, and when UPLO = ’L’ or ’l’, the leading n by n lower triangular part of the array A must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of A is not referenced.

LDA

LDA is INTEGER On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When SIDE = ’L’ or ’l’ then LDA must be at least max( 1, m ), otherwise LDA must be at least max( 1, n ).

B

B is REAL array, dimension ( LDB, N ) Before entry, the leading m by n part of the array B must contain the matrix B.

LDB

LDB is INTEGER On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. LDB must be at least max( 1, m ).

BETA

BETA is REAL On entry, BETA specifies the scalar beta. When BETA is supplied as zero then C need not be set on input.

C

C is REAL array, dimension ( LDC, N ) Before entry, the leading m by n part of the array C must contain the matrix C, except when beta is zero, in which case C need not be set on entry. On exit, the array C is overwritten by the m by n updated matrix.

LDC

LDC is INTEGER On entry, LDC specifies the first dimension of C as declared in the calling (sub) program. LDC must be at least max( 1, m ).

AUTHORS

o Univ. of Tennessee

o Univ. of California Berkeley

o Univ. of Colorado Denver

o NAG Ltd.
 date:December 2016

FURTHER DETAILS

Level 3 Blas routine.
-- Written on 8-February-1989. Jack Dongarra, Argonne National Laboratory. Iain Duff, AERE Harwell. Jeremy Du Croz, Numerical Algorithms Group Ltd. Sven Hammarling, Numerical Algorithms Group Ltd.