dsytri(3P) Sun Performance Library dsytri(3P)NAMEdsytri - compute the inverse of a real symmetric indefinite matrix A
using the factorization A = U*D*U**T or A = L*D*L**T computed by DSYTRF
SYNOPSIS
SUBROUTINE DSYTRI(UPLO, N, A, LDA, IPIVOT, WORK, INFO)
CHARACTER * 1 UPLO
INTEGER N, LDA, INFO
INTEGER IPIVOT(*)
DOUBLE PRECISION A(LDA,*), WORK(*)
SUBROUTINE DSYTRI_64(UPLO, N, A, LDA, IPIVOT, WORK, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, LDA, INFO
INTEGER*8 IPIVOT(*)
DOUBLE PRECISION A(LDA,*), WORK(*)
F95 INTERFACE
SUBROUTINE SYTRI(UPLO, N, A, [LDA], IPIVOT, [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, LDA, INFO
INTEGER, DIMENSION(:) :: IPIVOT
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE SYTRI_64(UPLO, N, A, [LDA], IPIVOT, [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, LDA, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void dsytri(char uplo, int n, double *a, int lda, int *ipivot, int
*info);
void dsytri_64(char uplo, long n, double *a, long lda, long *ipivot,
long *info);
PURPOSEdsytri computes the inverse of a real symmetric indefinite matrix A
using the factorization A = U*D*U**T or A = L*D*L**T computed by
DSYTRF.
ARGUMENTS
UPLO (input)
Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix. = 'U': Upper trian‐
gular, form is A = U*D*U**T;
= 'L': Lower triangular, form is A = L*D*L**T.
N (input) The order of the matrix A. N >= 0.
A (input/output)
On entry, the block diagonal matrix D and the multipliers
used to obtain the factor U or L as computed by DSYTRF.
On exit, if INFO = 0, the (symmetric) inverse of the original
matrix. If UPLO = 'U', the upper triangular part of the
inverse is formed and the part of A below the diagonal is not
referenced; if UPLO = 'L' the lower triangular part of the
inverse is formed and the part of A above the diagonal is not
referenced.
LDA (input)
The leading dimension of the array A. LDA >= max(1,N).
IPIVOT (input)
Details of the interchanges and the block structure of D as
determined by DSYTRF.
WORK (workspace)
dimension(N)
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
inverse could not be computed.
6 Mar 2009 dsytri(3P)
