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---
:name: dpptri
:md5sum: aa52068aa972b2b1a3d2d96115563353
:category: :subroutine
:arguments:
- uplo:
:type: char
:intent: input
- n:
:type: integer
:intent: input
- ap:
:type: doublereal
:intent: input/output
:dims:
- n*(n+1)/2
- info:
:type: integer
:intent: output
:substitutions: {}
:fortran_help: " SUBROUTINE DPPTRI( UPLO, N, AP, INFO )\n\n\
* Purpose\n\
* =======\n\
*\n\
* DPPTRI computes the inverse of a real symmetric positive definite\n\
* matrix A using the Cholesky factorization A = U**T*U or A = L*L**T\n\
* computed by DPPTRF.\n\
*\n\n\
* Arguments\n\
* =========\n\
*\n\
* UPLO (input) CHARACTER*1\n\
* = 'U': Upper triangular factor is stored in AP;\n\
* = 'L': Lower triangular factor is stored in AP.\n\
*\n\
* N (input) INTEGER\n\
* The order of the matrix A. N >= 0.\n\
*\n\
* AP (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2)\n\
* On entry, the triangular factor U or L from the Cholesky\n\
* factorization A = U**T*U or A = L*L**T, packed columnwise as\n\
* a linear array. The j-th column of U or L is stored in the\n\
* array AP as follows:\n\
* if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;\n\
* if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.\n\
*\n\
* On exit, the upper or lower triangle of the (symmetric)\n\
* inverse of A, overwriting the input factor U or L.\n\
*\n\
* INFO (output) INTEGER\n\
* = 0: successful exit\n\
* < 0: if INFO = -i, the i-th argument had an illegal value\n\
* > 0: if INFO = i, the (i,i) element of the factor U or L is\n\
* zero, and the inverse could not be computed.\n\
*\n\n\
* =====================================================================\n\
*\n"
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