cpptrf-f(3)

cpptrf.f –

Synopsis

Functions/Subroutines

subroutine cpptrf (UPLO, N, AP, INFO)
CPPTRF

Function/Subroutine Documentation

subroutine cpptrf (characterUPLO, integerN, complex, dimension( * )AP, integerINFO)

CPPTRF

Purpose:

 CPPTRF computes the Cholesky factorization of a complex Hermitian
 positive definite matrix A stored in packed format.
 The factorization has the form
 A = U**H * U, if UPLO = 'U', or
 A = L * L**H, 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 is INTEGER
 The order of the matrix A. N >= 0.

 AP is COMPLEX array, dimension (N*(N+1)/2)
 On entry, the upper or lower triangle of the Hermitian 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**H*U or A = L*L**H, 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 Hermitian matrix A:
 a11 a12 a13 a14
 a22 a23 a24
 a33 a34 (aij = conjg(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 cpptrf.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.