DSYRK (3) Linux Manual Page

dsyrk.f –

Synopsis

Functions/Subroutines

subroutine dsyrk (UPLO, TRANS, N, K, ALPHA, A, LDA, BETA, C, LDC)
DSYRK

Function/Subroutine Documentation

subroutine dsyrk (characterUPLO, characterTRANS, integerN, integerK, double precisionALPHA, double precision, dimension(lda,*)A, integerLDA, double precisionBETA, double precision, dimension(ldc,*)C, integerLDC)

DSYRK Purpose:

 DSYRK performs one of the symmetric rank k operations

 C := alpha*A*A**T + beta*C,

 or

 C := alpha*A**T*A + beta*C,

 where alpha and beta are scalars, C is an n by n symmetric 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**T + beta*C.

 TRANS = ‘T’ or ‘t’ C := alpha*A**T*A + beta*C.

 TRANS = ‘C’ or ‘c’ C := alpha*A**T*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 = ‘T’ or ‘t’ or ‘C’ or ‘c’, K specifies the number

 of rows of the matrix A. K must be at least zero.

ALPHA

 ALPHA is DOUBLE PRECISION.

 On entry, ALPHA specifies the scalar alpha.

A

 A is DOUBLE PRECISION 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 DOUBLE PRECISION.

 On entry, BETA specifies the scalar beta.

C

 C is DOUBLE PRECISION 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 symmetric 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 symmetric 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.

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.

 

Definition at line 170 of file dsyrk.f.

Author

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