LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
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◆ ssfrk()

subroutine ssfrk ( character transr,
character uplo,
character trans,
integer n,
integer k,
real alpha,
real, dimension( lda, * ) a,
integer lda,
real beta,
real, dimension( * ) c )

SSFRK performs a symmetric rank-k operation for matrix in RFP format.

Download SSFRK + dependencies [TGZ] [ZIP] [TXT]

Purpose:
!>
!> Level 3 BLAS like routine for C in RFP Format.
!>
!> SSFRK 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 real 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
[in]TRANSR
!>          TRANSR is CHARACTER*1
!>          = 'N':  The Normal Form of RFP A is stored;
!>          = 'T':  The Transpose Form of RFP A is stored.
!>
[in]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.
!>
!>           Unchanged on exit.
!>
[in]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.
!>
!>           Unchanged on exit.
!>
[in]N
!>          N is INTEGER
!>           On entry, N specifies the order of the matrix C. N must be
!>           at least zero.
!>           Unchanged on exit.
!>
[in]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', K specifies the number of rows of the matrix A. K
!>           must be at least zero.
!>           Unchanged on exit.
!>
[in]ALPHA
!>          ALPHA is REAL
!>           On entry, ALPHA specifies the scalar alpha.
!>           Unchanged on exit.
!>
[in]A
!>          A is REAL array, 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.
!>           Unchanged on exit.
!>
[in]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 ).
!>           Unchanged on exit.
!>
[in]BETA
!>          BETA is REAL
!>           On entry, BETA specifies the scalar beta.
!>           Unchanged on exit.
!>
[in,out]C
!>          C is REAL array, dimension (NT)
!>           NT = N*(N+1)/2. On entry, the symmetric matrix C in RFP
!>           Format. RFP Format is described by TRANSR, UPLO and N.
!>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.