NAME zher2k - 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 ZHER2K (UPLO, TRANS, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC) CHARACTER*1 UPLO, TRANS INTEGER N, K, LDA, LDB, LDC DOUBLE PRECISION BETA COMPLEX*16 ALPHA COMPLEX*16 A( LDA, * ), B( LDB, * ), C( LDC, * ) #include <sunperf.h> void zher2k(char uplo, char trans, int n, int k, doublecom- plex *zalpha, doublecomplex *za, int lda, doub- lecomplex * b, int ldb, double dbeta, doublecom- plex *zc, int ldc) ; PURPOSE ZHER2K 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. PARAMETERS UPLO - 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. Unchanged on exit. TRANS - CHARACTER*1. On entry, TRANS specifies the operation to be performed as follows: TRANS = 'N' or 'n' C := alpha*A*conjg( B' ) + conjg( alpha )*B*conjg( A' ) + beta*C. TRANS = 'C' or 'c' C := alpha*conjg( A' )*B + conjg( alpha )*conjg( B' )*A + beta*C. Unchanged on exit. N - INTEGER. On entry, N specifies the order of the matrix C. N must be at least zero. Unchanged on exit. K - INTEGER. On entry with TRANS = 'N' or 'n', K specifies the number of columns of the matrices A and B, and on entry with TRANS = 'C' or 'c', K speci- fies the number of rows of the matrices A and B. K must be at least zero. Unchanged on exit. ALPHA - COMPLEX*16. On entry, ALPHA specifies the scalar alpha. Unchanged on exit. A - COMPLEX*16 array of DIMENSION ( LDA, ka ), where ka is k when TRANS = 'N' or 'n', and is n other- wise. Before entry with TRANS = 'N' or 'n', the lead- ing 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 - 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 ). Unchanged on exit. B - COMPLEX*16 array of DIMENSION ( LDB, kb ), where kb is k when TRANS = 'N' or 'n', and is n other- wise. Before entry with TRANS = 'N' or 'n', the lead- ing 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 - INTEGER. On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. When TRANS = '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 - DOUBLE PRECISION. On entry, BETA specifies the scalar beta. Unchanged on exit. C - COMPLEX*16 array of DIMENSION ( LDC, n ). Before entry with UPLO = 'U' or 'u', the lead- ing n by n upper triangular part of the array C must contain the upper triangular part of the hermitian matrix and the strictly lower triangu- lar part of C is not referenced. On exit, the upper triangular part of the array C is overwrit- ten by the upper triangular part of the updated matrix. Before entry with UPLO = 'L' or 'l', the lead- ing n by n lower triangular part of the array C must contain the lower triangular part of the hermitian matrix and the strictly upper triangu- lar part of C is not referenced. On exit, the lower triangular part of the array C is overwrit- ten by the lower triangular part of the updated matrix. Note that the imaginary parts of the diagonal ele- ments need not be set, they are assumed to be zero, and on exit they are set to zero. LDC - 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 ). Unchanged on exit.
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