dsptri(3P) Sun Performance Library dsptri(3P)NAMEdsptri - compute the inverse of a real symmetric indefinite matrix A in
packed storage using the factorization A = U*D*U**T or A = L*D*L**T
computed by DSPTRF
SYNOPSIS
SUBROUTINE DSPTRI(UPLO, N, AP, IPIVOT, WORK, INFO)
CHARACTER * 1 UPLO
INTEGER N, INFO
INTEGER IPIVOT(*)
DOUBLE PRECISION AP(*), WORK(*)
SUBROUTINE DSPTRI_64(UPLO, N, AP, IPIVOT, WORK, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, INFO
INTEGER*8 IPIVOT(*)
DOUBLE PRECISION AP(*), WORK(*)
F95 INTERFACE
SUBROUTINE SPTRI(UPLO, [N], AP, IPIVOT, [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, INFO
INTEGER, DIMENSION(:) :: IPIVOT
REAL(8), DIMENSION(:) :: AP, WORK
SUBROUTINE SPTRI_64(UPLO, [N], AP, IPIVOT, [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT
REAL(8), DIMENSION(:) :: AP, WORK
C INTERFACE
#include <sunperf.h>
void dsptri(char uplo, int n, double *a, int *ipivot, int *info);
void dsptri_64(char uplo, long n, double *a, long *ipivot, long *info);
PURPOSEdsptri computes the inverse of a real symmetric indefinite matrix A in
packed storage using the factorization A = U*D*U**T or A = L*D*L**T
computed by DSPTRF.
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.
AP (input/output)
Double precision array, dimension (N*(N+1)/2) On entry, the
block diagonal matrix D and the multipliers used to obtain
the factor U or L as computed by DSPTRF, stored as a packed
triangular matrix.
On exit, if INFO = 0, the (symmetric) inverse of the original
matrix, stored as a packed triangular matrix. The j-th column
of inv(A) is stored in the array AP as follows: if UPLO =
'U', AP(i + (j-1)*j/2) = inv(A)(i,j) for 1<=i<=j; if UPLO =
'L', AP(i + (j-1)*(2n-j)/2) = inv(A)(i,j) for j<=i<=n.
IPIVOT (input)
Integer array, dimension (N) Details of the interchanges and
the block structure of D as determined by DSPTRF.
WORK (workspace)
Double precision array, 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 dsptri(3P)
