[ Previous  Next  Table of Contents  Index  Library Home 
Legal 
Search ]
Technical Reference: Base Operating System and Extensions , Volume 2
Performs Hermitian rank 2k
operations.
BLAS Library
(libblas.a)
SUBROUTINE CHER2K(UPLO, TRANS, N, K, ALPHA,
A, LDA, B, LDB, C, LDC)
CHARACTER*1 UPLO, TRANS
INTEGER N, K, LDA, LDB, LDC
REAL BETA
COMPLEX ALPHA
COMPLEX A(LDA,*), B(LDB,*), C(LDC,*)
SUBROUTINE ZHER2K(UPLO, TRANS, N, K, ALPHA,
A, LDA, B, LDB, 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,*)
The CHER2K or
ZHER2K subroutine 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.
UPLO
 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
 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
 On entry, N specifies the order of the matrix
C; N must be at least 0; unchanged on
exit.

K
 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 specifies the number of rows of the matrices
A and B; K must be at least 0;
unchanged on exit.

ALPHA
 On entry, ALPHA specifies the scalar alpha; unchanged on
exit.

A
 An array of dimension ( LDA, KA ), where
KA is K when TRANS = 'N' or
'n', and is N otherwise; on 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; unchanged on
exit.

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

B
 An array of dimension ( LDB, KB ), where
KB is K when TRANS = 'N' or
'n', and is N otherwise; on entry with
TRANS = '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
 On entry, LDB specifies the first dimension of B as
declared in the calling (sub) program. When TRANS =
'N' or 'n', LDB must be at least max( 1,
N ); otherwise LDB must be at least max( 1,
K ); unchanged on exit.

BETA
 On entry, BETA specifies the scalar beta; unchanged on
exit.

C
 An array of dimension ( LDC, N ); on 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 reference; on exit,
the upper triangular part of the array C is overwritten by the
upper triangular part of the updated matrix; on 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. The imaginary parts of the
diagonal elements need not be set, they are assumed to be 0, and on exit they
are set to 0.

LDC
 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.

[ Previous  Next  Table of Contents  Index 
Library Home 
Legal 
Search ]