redhat man page for dpptri

DPPTRI(l)								 )								 DPPTRI(l)

NAME
       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 com-
       puted by DPPTRF

SYNOPSIS
       SUBROUTINE DPPTRI( UPLO, N, AP, INFO )

	   CHARACTER	  UPLO

	   INTEGER	  INFO, N

	   DOUBLE	  PRECISION AP( * )

PURPOSE
       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  com-
       puted by DPPTRF.

ARGUMENTS
       UPLO    (input) CHARACTER*1
	       = 'U':  Upper triangular factor is stored in AP;
	       = 'L':  Lower triangular factor is stored in AP.

       N       (input) INTEGER
	       The order of the matrix A.  N >= 0.

       AP      (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2)
	       On  entry,  the	triangular  factor  U or L from the Cholesky factorization A = U**T*U or A = L*L**T, packed columnwise as a linear
	       array.  The j-th column of U or L is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for  1<=i<=j;	if
	       UPLO = 'L', AP(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.

       INFO    (output) INTEGER
	       = 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.

LAPACK version 3.0						   15 June 2000 							 DPPTRI(l)