cherk.f(3)

NAME
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

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

    K

              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

              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

              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

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