cpttrf-f(3)

cpttrf.f –

Synopsis

Functions/Subroutines

subroutine cpttrf (N, D, E, INFO)
CPTTRF

Function/Subroutine Documentation

subroutine cpttrf (integerN, real, dimension( * )D, complex, dimension( * )E, integerINFO)

CPTTRF

Purpose:

 CPTTRF computes the L*D*L**H factorization of a complex Hermitian
 positive definite tridiagonal matrix A. The factorization may also
 be regarded as having the form A = U**H *D*U.

 

Parameters:

N

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

D

 D is REAL 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**H factorization of A.

E

 E is COMPLEX array, dimension (N-1)
 On entry, the (n-1) subdiagonal elements of the tridiagonal
 matrix A. On exit, the (n-1) subdiagonal elements of the
 unit bidiagonal factor L from the L*D*L**H factorization of A.
 E can also be regarded as the superdiagonal of the unit
 bidiagonal factor U from the U**H *D*U factorization of A.

INFO

 INFO is INTEGER
 = 0: successful exit
 < 0: if INFO = -k, the k-th 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 93 of file cpttrf.f.

Author

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