dpptri - compute the inverse of a real symmetric positive definite matrix A using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPPTRF
SUBROUTINE DPPTRI( UPLO, N, A, INFO) CHARACTER * 1 UPLO INTEGER N, INFO DOUBLE PRECISION A(*)
SUBROUTINE DPPTRI_64( UPLO, N, A, INFO) CHARACTER * 1 UPLO INTEGER*8 N, INFO DOUBLE PRECISION A(*)
SUBROUTINE PPTRI( UPLO, N, A, [INFO]) CHARACTER(LEN=1) :: UPLO INTEGER :: N, INFO REAL(8), DIMENSION(:) :: A
SUBROUTINE PPTRI_64( UPLO, N, A, [INFO]) CHARACTER(LEN=1) :: UPLO INTEGER(8) :: N, INFO REAL(8), DIMENSION(:) :: A
#include <sunperf.h>
void dpptri(char uplo, int n, double *a, int *info);
void dpptri_64(char uplo, long n, double *a, long *info);
dpptri computes the inverse of a real symmetric positive definite matrix A using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPPTRF.
= 'U': Upper triangular factor is stored in A;
= 'L': Lower triangular factor is stored in A.
U(i,j)
for 1 < =i < =j;
if UPLO = 'L', A(i + (j-1)*(2n-j)/2) = L(i,j)
for j < =i < =n.
On exit, the upper or lower triangle of the (symmetric) inverse of A, overwriting the input factor U or L.
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, the (i,i) element of the factor U or L is zero, and the inverse could not be computed.