stptri.f(3)							      LAPACK							       stptri.f(3)

NAME

       stptri.f -

SYNOPSIS

   Functions/Subroutines
       subroutine stptri (UPLO, DIAG, N, AP, INFO)
	   STPTRI

Function/Subroutine Documentation
   subroutine stptri (characterUPLO, characterDIAG, integerN, real, dimension( * )AP, integerINFO)
       STPTRI

       Purpose:

	    STPTRI 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 non-unit triangular;
		     = 'U':  A is unit triangular.

	   N

		     N is INTEGER
		     The order of the matrix A.  N >= 0.

	   AP

		     AP is REAL array, dimension (N*(N+1)/2)
		     On entry, the upper or lower triangular matrix A, stored
		     columnwise in a linear array.  The j-th column of A is stored
		     in the array AP as follows:
		     if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
		     if UPLO = 'L', AP(i + (j-1)*((2*n-j)/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 i-th 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+I-1) = A(I,J)		  AP(JC+I-J) = 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 stptri.f.

Author
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Version 3.4.1							  Sun May 26 2013						       stptri.f(3)