spptrf.f(3)							      LAPACK							       spptrf.f(3)

NAME

       spptrf.f -

SYNOPSIS

   Functions/Subroutines
       subroutine spptrf (UPLO, N, AP, INFO)
	   SPPTRF

Function/Subroutine Documentation
   subroutine spptrf (characterUPLO, integerN, real, dimension( * )AP, integerINFO)
       SPPTRF

       Purpose:

	    SPPTRF computes the Cholesky factorization of a real symmetric
	    positive definite matrix A stored in packed format.

	    The factorization has the form
	       A = U**T * U,  if UPLO = 'U', or
	       A = L  * L**T,  if UPLO = 'L',
	    where U is an upper triangular matrix and L is lower triangular.

       Parameters:
	   UPLO

		     UPLO is CHARACTER*1
		     = 'U':  Upper triangle of A is stored;
		     = 'L':  Lower triangle of A is stored.

	   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 triangle of the symmetric matrix
		     A, packed 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)*(2n-j)/2) = A(i,j) for j<=i<=n.
		     See below for further details.

		     On exit, if INFO = 0, the triangular factor U or L from the
		     Cholesky factorization A = U**T*U or A = L*L**T, in the same
		     storage format as A.

	   INFO

		     INFO is INTEGER
		     = 0:  successful exit
		     < 0:  if INFO = -i, the i-th argument had an illegal value
		     > 0:  if INFO = i, the leading minor of order i is not
			   positive definite, and the factorization could not be
			   completed.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Further Details:

	     The packed storage scheme is illustrated by the following example
	     when N = 4, UPLO = 'U':

	     Two-dimensional storage of the symmetric matrix A:

		a11 a12 a13 a14
		    a22 a23 a24
			a33 a34     (aij = aji)
			    a44

	     Packed storage of the upper triangle of A:

	     AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ]

       Definition at line 120 of file spptrf.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.1							  Sun May 26 2013						       spptrf.f(3)