cherk-f(3)

cherk.f –

Synopsis

Functions/Subroutines

subroutine cherk (UPLO, TRANS, N, K, ALPHA, A, LDA, BETA, C, LDC)
CHERK

Function/Subroutine Documentation

subroutine cherk (characterUPLO, characterTRANS, integerN, integerK, realALPHA, complex, dimension(lda,)A, integerLDA, realBETA, complex, dimension(ldc,)C, integerLDC)

CHERK Purpose:

 CHERK performs one of the hermitian rank k operations
 C := alpha*A*A**H + beta*C,
 or
 C := alpha*A**H*A + beta*C,
 where alpha and beta are real scalars, C is an n by n hermitian
 matrix and A is an n by k matrix in the first case and a k by n
 matrix in the second case.

Parameters:

UPLO

 UPLO is CHARACTER*1
 On entry, UPLO specifies whether the upper or lower
 triangular part of the array C is to be referenced as
 follows:
 UPLO = 'U' or 'u' Only the upper triangular part of C
 is to be referenced.
 UPLO = 'L' or 'l' Only the lower triangular part of C
 is to be referenced.

TRANS

 TRANS is CHARACTER*1
 On entry, TRANS specifies the operation to be performed as
 follows:
 TRANS = 'N' or 'n' C := alpha*A*A**H + beta*C.
 TRANS = 'C' or 'c' C := alpha*A**H*A + beta*C.

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

 K is INTEGER
 On entry with TRANS = 'N' or 'n', K specifies the number
 of columns of the matrix A, and on entry with
 TRANS = 'C' or 'c', K specifies the number of rows of the
 matrix A. K must be at least zero.

ALPHA

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

 A is COMPLEX array of DIMENSION ( LDA, ka ), where ka is
 k when TRANS = 'N' or 'n', and is n otherwise.
 Before entry with TRANS = 'N' or 'n', the leading n by k
 part of the array A must contain the matrix A, otherwise
 the leading k by n part of the array A must contain the
 matrix A.

LDA

 LDA is INTEGER
 On entry, LDA specifies the first dimension of A as declared
 in the calling (sub) program. When TRANS = 'N' or 'n'
 then LDA must be at least max( 1, n ), otherwise LDA must
 be at least max( 1, k ).

BETA

 BETA is REAL
 On entry, BETA specifies the scalar beta.

 C is COMPLEX array of DIMENSION ( LDC, n ).
 Before entry with UPLO = 'U' or 'u', the leading n by n
 upper triangular part of the array C must contain the upper
 triangular part of the hermitian matrix and the strictly
 lower triangular part of C is not referenced. On exit, the
 upper triangular part of the array C is overwritten by the
 upper triangular part of the updated matrix.
 Before entry with UPLO = 'L' or 'l', the leading n by n
 lower triangular part of the array C must contain the lower
 triangular part of the hermitian matrix and the strictly
 upper triangular part of C is not referenced. On exit, the
 lower triangular part of the array C is overwritten by the
 lower triangular part of the updated matrix.
 Note that the imaginary parts of the diagonal elements need
 not be set, they are assumed to be zero, and on exit they
 are set to zero.

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, n ).

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

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.
 -- Modified 8-Nov-93 to set C(J,J) to REAL( C(J,J) ) when BETA = 1.
 Ed Anderson, Cray Research Inc.

Definition at line 174 of file cherk.f.

Author