slavsp.f3
Usage
Functions/Subroutines
subroutine slavsp (uplo, trans, diag, n, nrhs, a, ipiv, b, ldb, info)
SLAVSP
Function/Subroutine Documentation
subroutine slavsp (character uplo, character trans, character diag, integer n, integer nrhs, real, dimension( * ) a, integer, dimension( * ) ipiv, real, dimension( ldb, * ) b, integer ldb, integer info)
SLAVSP
Purpose:
!> !> SLAVSP performs one of the matrix-vector operations !> x := A*x or x := A'*x, !> where x is an N element vector and A is one of the factors !> from the block U*D*U' or L*D*L' factorization computed by SSPTRF. !> !> If TRANS = 'N', multiplies by U or U * D (or L or L * D) !> If TRANS = 'T', multiplies by U' or D * U' (or L' or D * L' ) !> If TRANS = 'C', multiplies by U' or D * U' (or L' or D * L' ) !>
Parameters
UPLO
!> UPLO is CHARACTER*1 !> Specifies whether the factor stored in A is upper or lower !> triangular. !> = 'U': Upper triangular !> = 'L': Lower triangular !>
TRANS
!> TRANS is CHARACTER*1 !> Specifies the operation to be performed: !> = 'N': x := A*x !> = 'T': x := A'*x !> = 'C': x := A'*x !>
DIAG
!> DIAG is CHARACTER*1 !> Specifies whether or not the diagonal blocks are unit !> matrices. If the diagonal blocks are assumed to be unit, !> then A = U or A = L, otherwise A = U*D or A = L*D. !> = 'U': Diagonal blocks are assumed to be unit matrices. !> = 'N': Diagonal blocks are assumed to be non-unit matrices. !>
N
!> N is INTEGER !> The number of rows and columns of the matrix A. N >= 0. !>
NRHS
!> NRHS is INTEGER !> The number of right hand sides, i.e., the number of vectors !> x to be multiplied by A. NRHS >= 0. !>
A
!> A is REAL array, dimension (N*(N+1)/2) !> The block diagonal matrix D and the multipliers used to !> obtain the factor U or L, stored as a packed triangular !> matrix as computed by SSPTRF. !>
IPIV
!> IPIV is INTEGER array, dimension (N) !> The pivot indices from SSPTRF. !>
B
!> B is REAL array, dimension (LDB,NRHS) !> On entry, B contains NRHS vectors of length N. !> On exit, B is overwritten with the product A * B. !>
LDB
!> LDB is INTEGER !> The leading dimension of the array B. LDB >= max(1,N). !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -k, the k-th argument had an illegal value !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 128 of file slavsp.f.