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dpptrf.f(3)				      LAPACK				      dpptrf.f(3)

       dpptrf.f -

       subroutine dpptrf (UPLO, N, AP, INFO)

Function/Subroutine Documentation
   subroutine dpptrf (characterUPLO, integerN, double precision, dimension( * )AP, integerINFO)


	    DPPTRF 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.


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


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


		     AP is DOUBLE PRECISION 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 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

	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

	   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)

	     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 dpptrf.f.

       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      dpptrf.f(3)
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