cher2k

NAME

cher2k - perform one of the Hermitian rank 2k operations C := alpha*A*conjg( B' ) + conjg( alpha )*B*conjg( A' ) + beta*C or C := alpha*conjg( A' )*B + conjg( alpha )*conjg( B' )*A + beta*C

SYNOPSIS

  SUBROUTINE CHER2K( UPLO, TRANSA, N, K, ALPHA, A, LDA, B, LDB, BETA, 
 *      C, LDC)
  CHARACTER * 1 UPLO, TRANSA
  COMPLEX ALPHA
  COMPLEX A(LDA,*), B(LDB,*), C(LDC,*)
  INTEGER N, K, LDA, LDB, LDC
  REAL BETA
 
  SUBROUTINE CHER2K_64( UPLO, TRANSA, N, K, ALPHA, A, LDA, B, LDB, 
 *      BETA, C, LDC)
  CHARACTER * 1 UPLO, TRANSA
  COMPLEX ALPHA
  COMPLEX A(LDA,*), B(LDB,*), C(LDC,*)
  INTEGER*8 N, K, LDA, LDB, LDC
  REAL BETA

F95 INTERFACE

  SUBROUTINE HER2K( UPLO, [TRANSA], [N], [K], ALPHA, A, [LDA], B, [LDB], 
 *       BETA, C, [LDC])
  CHARACTER(LEN=1) :: UPLO, TRANSA
  COMPLEX :: ALPHA
  COMPLEX, DIMENSION(:,:) :: A, B, C
  INTEGER :: N, K, LDA, LDB, LDC
  REAL :: BETA
 
  SUBROUTINE HER2K_64( UPLO, [TRANSA], [N], [K], ALPHA, A, [LDA], B, 
 *       [LDB], BETA, C, [LDC])
  CHARACTER(LEN=1) :: UPLO, TRANSA
  COMPLEX :: ALPHA
  COMPLEX, DIMENSION(:,:) :: A, B, C
  INTEGER(8) :: N, K, LDA, LDB, LDC
  REAL :: BETA

C INTERFACE

#include <sunperf.h>

void cher2k(char uplo, char transa, int n, int k, complex alpha, complex *a, int lda, complex *b, int ldb, float beta, complex *c, int ldc);

void cher2k_64(char uplo, char transa, long n, long k, complex alpha, complex *a, long lda, complex *b, long ldb, float beta, complex *c, long ldc);

PURPOSE

cher2k K performs one of the Hermitian rank 2k operations C := alpha*A*conjg( B' ) + conjg( alpha )*B*conjg( A' ) + beta*C or C := alpha*conjg( A' )*B + conjg( alpha )*conjg( B' )*A + beta*C where alpha and beta are scalars with beta real, C is an n by n Hermitian matrix and A and B are n by k matrices in the first case and k by n matrices in the second case.

ARGUMENTS

* UPLO (input)

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.

Unchanged on exit.

* TRANSA (input)

On entry, TRANSA specifies the operation to be performed as follows:

TRANSA = 'N' or 'n' C := alpha*A*conjg( B' ) + conjg( alpha )*B*conjg( A' ) + beta*C.

TRANSA = 'C' or 'c' C := alpha*conjg( A' )*B + conjg( alpha )*conjg( B' )*A + beta*C.

Unchanged on exit.

* N (input)

On entry, N specifies the order of the matrix C. N must be at least zero. Unchanged on exit.

* K (input)

On entry with TRANSA = 'N' or 'n', K specifies the number of columns of the matrices A and B, and on entry with TRANSA = 'C' or 'c', K specifies the number of rows of the matrices A and B. K must be at least zero. Unchanged on exit.

* ALPHA (input)

On entry, ALPHA specifies the scalar alpha. Unchanged on exit.

* A (input)

k when TRANSA = 'N' or 'n', and is n otherwise. Before entry with TRANSA = '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. Unchanged on exit.

* LDA (input)

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

* B (input)

k when TRANSA = 'N' or 'n', and is n otherwise. Before entry with TRANSA = 'N' or 'n', the leading n by k part of the array B must contain the matrix B, otherwise the leading k by n part of the array B must contain the matrix B. Unchanged on exit.

* LDB (input)

On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. When TRANSA = 'N' or 'n' then LDB must be at least max( 1, n ), otherwise LDB must be at least max( 1, k ). Unchanged on exit.

* BETA (input)

On entry, BETA specifies the scalar beta. Unchanged on exit.

* C (input/output)

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 (input)

On entry, LDC specifies the first dimension of C as declared in the calling (sub) program. LDC must be at least max( 1, n ). Unchanged on exit.