
dtptri.f(3) LAPACK dtptri.f(3)
NAME
dtptri.f 
SYNOPSIS
Functions/Subroutines
subroutine dtptri (UPLO, DIAG, N, AP, INFO)
DTPTRI
Function/Subroutine Documentation
subroutine dtptri (characterUPLO, characterDIAG, integerN, double precision, dimension( * )AP,
integerINFO)
DTPTRI
Purpose:
DTPTRI computes the inverse of a real upper or lower triangular
matrix A stored in packed format.
Parameters:
UPLO
UPLO is CHARACTER*1
= 'U': A is upper triangular;
= 'L': A is lower triangular.
DIAG
DIAG is CHARACTER*1
= 'N': A is nonunit triangular;
= 'U': A is unit triangular.
N
N is INTEGER
The order of the matrix A. N >= 0.
AP
AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
On entry, the upper or lower triangular matrix A, stored
columnwise in a linear array. The jth column of A is stored
in the array AP as follows:
if UPLO = 'U', AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j1)*((2*nj)/2) = A(i,j) for j<=i<=n.
See below for further details.
On exit, the (triangular) inverse of the original matrix, in
the same packed storage format.
INFO
INFO is INTEGER
= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
> 0: if INFO = i, A(i,i) is exactly zero. The triangular
matrix is singular and its inverse can not be computed.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011
Further Details:
A triangular matrix A can be transferred to packed storage using one
of the following program segments:
UPLO = 'U': UPLO = 'L':
JC = 1 JC = 1
DO 2 J = 1, N DO 2 J = 1, N
DO 1 I = 1, J DO 1 I = J, N
AP(JC+I1) = A(I,J) AP(JC+IJ) = A(I,J)
1 CONTINUE 1 CONTINUE
JC = JC + J JC = JC + N  J + 1
2 CONTINUE 2 CONTINUE
Definition at line 118 of file dtptri.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 dtptri.f(3) 
