

 
Manual Reference Pages  SDTTRF (l)
NAME
SDTTRF  compute an LU factorization of a complex tridiagonal matrix A using elimination without partial pivoting
CONTENTS
Synopsis
Purpose
Arguments
SYNOPSIS
SUBROUTINE SDTTRF(

N, DL, D, DU, INFO )


INTEGER
INFO, N


REAL
D( * ), DL( * ), DU( * )


PURPOSE
SDTTRF computes an LU factorization of a complex tridiagonal matrix A using elimination without partial pivoting.
The factorization has the form
A = L * U
where L is a product of unit lower bidiagonal
matrices and U is upper triangular with nonzeros in only the main
diagonal and first superdiagonal.
ARGUMENTS
N (input) INTEGER
 
The order of the matrix A. N >= 0.

DL (input/output) COMPLEX array, dimension (N1)
 
On entry, DL must contain the (n1) subdiagonal elements of
A.
On exit, DL is overwritten by the (n1) multipliers that
define the matrix L from the LU factorization of A.

D (input/output) COMPLEX array, dimension (N)
 
On entry, D must contain the diagonal elements of A.
On exit, D is overwritten by the n diagonal elements of the
upper triangular matrix U from the LU factorization of A.

DU (input/output) COMPLEX array, dimension (N1)
 
On entry, DU must contain the (n1) superdiagonal elements
of A.
On exit, DU is overwritten by the (n1) elements of the first
superdiagonal of U.

INFO (output) INTEGER
 
= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
> 0: if INFO = i, U(i,i) is exactly zero. The factorization
has been completed, but the factor U is exactly
singular, and division by zero will occur if it is used
to solve a system of equations.


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