redhat man page for cgtsv

CGTSV(l)								 )								  CGTSV(l)

NAME
       CGTSV - solve the equation  A*X = B,

SYNOPSIS
       SUBROUTINE CGTSV( N, NRHS, DL, D, DU, B, LDB, INFO )

	   INTEGER	 INFO, LDB, N, NRHS

	   COMPLEX	 B( LDB, * ), D( * ), DL( * ), DU( * )

PURPOSE
       CGTSV solves the equation A*X = B, where A is an N-by-N tridiagonal matrix, by Gaussian elimination with partial pivoting.

       Note that the equation  A'*X = B  may be solved by interchanging the order of the arguments DU and DL.

ARGUMENTS
       N       (input) INTEGER
	       The order of the matrix A.  N >= 0.

       NRHS    (input) INTEGER
	       The number of right hand sides, i.e., the number of columns of the matrix B.  NRHS >= 0.

       DL      (input/output) COMPLEX array, dimension (N-1)
	       On  entry,  DL  must  contain  the (n-1) subdiagonal elements of A.  On exit, DL is overwritten by the (n-2) elements of the second
	       superdiagonal of the upper triangular matrix U from the LU factorization of A, in DL(1), ..., DL(n-2).

       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 U.

       DU      (input/output) COMPLEX array, dimension (N-1)
	       On entry, DU must contain the (n-1) superdiagonal elements of A.  On exit, DU is overwritten by the (n-1)  elements  of	the  first
	       superdiagonal of U.

       B       (input/output) COMPLEX array, dimension (LDB,NRHS)
	       On entry, the N-by-NRHS right hand side matrix B.  On exit, if INFO = 0, the N-by-NRHS solution matrix X.

       LDB     (input) INTEGER
	       The leading dimension of the array B.  LDB >= max(1,N).

       INFO    (output) INTEGER
	       = 0:  successful exit
	       < 0:  if INFO = -i, the i-th argument had an illegal value
	       > 0:  if INFO = i, U(i,i) is exactly zero, and the solution has not been computed.  The factorization has not been completed unless
	       i = N.

LAPACK version 3.0						   15 June 2000 							  CGTSV(l)