cgttrf(l) [redhat man page]

CGTTRF(l)								 )								 CGTTRF(l)

NAME

       CGTTRF - compute an LU factorization of a complex tridiagonal matrix A using elimination with partial pivoting and row interchanges

SYNOPSIS

       SUBROUTINE CGTTRF( N, DL, D, DU, DU2, IPIV, INFO )

	   INTEGER	  INFO, N

	   INTEGER	  IPIV( * )

	   COMPLEX	  D( * ), DL( * ), DU( * ), DU2( * )

PURPOSE

       CGTTRF  computes  an  LU factorization of a complex tridiagonal matrix A using elimination with partial pivoting and row interchanges.  The
       factorization has the form
	  A = L * U
       where L is a product of permutation and unit lower bidiagonal matrices and U is upper triangular with nonzeros in only  the  main  diagonal
       and first two superdiagonals.

ARGUMENTS

       N       (input) INTEGER
	       The order of the matrix A.

       DL      (input/output) COMPLEX array, dimension (N-1)
	       On entry, DL must contain the (n-1) sub-diagonal elements of A.

	       On exit, DL is overwritten by the (n-1) 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 (N-1)
	       On entry, DU must contain the (n-1) super-diagonal elements of A.

	       On exit, DU is overwritten by the (n-1) elements of the first super-diagonal of U.

       DU2     (output) COMPLEX array, dimension (N-2)
	       On exit, DU2 is overwritten by the (n-2) elements of the second super-diagonal of U.

       IPIV    (output) INTEGER array, dimension (N)
	       The pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i).  IPIV(i) will always be either i or i+1;
	       IPIV(i) = i indicates a row interchange was not required.

       INFO    (output) INTEGER
	       = 0:  successful exit
	       < 0:  if INFO = -k, the k-th argument had an illegal value
	       > 0:  if INFO = k, U(k,k) 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.

LAPACK version 3.0						   15 June 2000 							 CGTTRF(l)

zgttrf.f(3)							      LAPACK							       zgttrf.f(3)

NAME

       zgttrf.f -

SYNOPSIS

   Functions/Subroutines
       subroutine zgttrf (N, DL, D, DU, DU2, IPIV, INFO)
	   ZGTTRF

Function/Subroutine Documentation
   subroutine zgttrf (integerN, complex*16, dimension( * )DL, complex*16, dimension( * )D, complex*16, dimension( * )DU, complex*16, dimension( *
       )DU2, integer, dimension( * )IPIV, integerINFO)
       ZGTTRF

       Purpose:

	    ZGTTRF computes an LU factorization of a complex tridiagonal matrix A
	    using elimination with partial pivoting and row interchanges.

	    The factorization has the form
	       A = L * U
	    where L is a product of permutation and unit lower bidiagonal
	    matrices and U is upper triangular with nonzeros in only the main
	    diagonal and first two superdiagonals.

       Parameters:
	   N

		     N is INTEGER
		     The order of the matrix A.

	   DL

		     DL is COMPLEX*16 array, dimension (N-1)
		     On entry, DL must contain the (n-1) sub-diagonal elements of
		     A.

		     On exit, DL is overwritten by the (n-1) multipliers that
		     define the matrix L from the LU factorization of A.

	   D

		     D is COMPLEX*16 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

		     DU is COMPLEX*16 array, dimension (N-1)
		     On entry, DU must contain the (n-1) super-diagonal elements
		     of A.

		     On exit, DU is overwritten by the (n-1) elements of the first
		     super-diagonal of U.

	   DU2

		     DU2 is COMPLEX*16 array, dimension (N-2)
		     On exit, DU2 is overwritten by the (n-2) elements of the
		     second super-diagonal of U.

	   IPIV

		     IPIV is INTEGER array, dimension (N)
		     The pivot indices; for 1 <= i <= n, row i of the matrix was
		     interchanged with row IPIV(i).  IPIV(i) will always be either
		     i or i+1; IPIV(i) = i indicates a row interchange was not
		     required.

	   INFO

		     INFO is INTEGER
		     = 0:  successful exit
		     < 0:  if INFO = -k, the k-th argument had an illegal value
		     > 0:  if INFO = k, U(k,k) 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.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 125 of file zgttrf.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.1							  Sun May 26 2013						       zgttrf.f(3)