dpttrf.f (3)  Linux Manuals
NAME
dpttrf.f 
SYNOPSIS
Functions/Subroutines
subroutine dpttrf (N, D, E, INFO)
DPTTRF
Function/Subroutine Documentation
subroutine dpttrf (integerN, double precision, dimension( * )D, double precision, dimension( * )E, integerINFO)
DPTTRF
Purpose:

DPTTRF computes the L*D*L**T factorization of a real symmetric positive definite tridiagonal matrix A. The factorization may also be regarded as having the form A = U**T*D*U.
Parameters:

N
N is INTEGER The order of the matrix A. N >= 0.
DD is DOUBLE PRECISION array, dimension (N) On entry, the n diagonal elements of the tridiagonal matrix A. On exit, the n diagonal elements of the diagonal matrix D from the L*D*L**T factorization of A.
EE is DOUBLE PRECISION array, dimension (N1) On entry, the (n1) subdiagonal elements of the tridiagonal matrix A. On exit, the (n1) subdiagonal elements of the unit bidiagonal factor L from the L*D*L**T factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the U**T*D*U factorization of A.
INFOINFO is INTEGER = 0: successful exit < 0: if INFO = k, the kth argument had an illegal value > 0: if INFO = k, the leading minor of order k is not positive definite; if k < N, the factorization could not be completed, while if k = N, the factorization was completed, but D(N) <= 0.
Author:

Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
 September 2012
Definition at line 92 of file dpttrf.f.
Author
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