redhat man page for dpttrs

DPTTRS(l)								 )								 DPTTRS(l)

NAME
       DPTTRS - solve a tridiagonal system of the form A * X = B using the L*D*L' factorization of A computed by DPTTRF

SYNOPSIS
       SUBROUTINE DPTTRS( N, NRHS, D, E, B, LDB, INFO )

	   INTEGER	  INFO, LDB, N, NRHS

	   DOUBLE	  PRECISION B( LDB, * ), D( * ), E( * )

PURPOSE
       DPTTRS  solves  a  tridiagonal  system of the form A * X = B using the L*D*L' factorization of A computed by DPTTRF. D is a diagonal matrix
       specified in the vector D, L is a unit bidiagonal matrix whose subdiagonal is specified in the vector E, and X and B are N by  NRHS  matri-
       ces.

ARGUMENTS
       N       (input) INTEGER
	       The order of the tridiagonal 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.

       D       (input) DOUBLE PRECISION array, dimension (N)
	       The n diagonal elements of the diagonal matrix D from the L*D*L' factorization of A.

       E       (input) DOUBLE PRECISION array, dimension (N-1)
	       The  (n-1)  subdiagonal elements of the unit bidiagonal factor L from the L*D*L' factorization of A.  E can also be regarded as the
	       superdiagonal of the unit bidiagonal factor U from the factorization A = U'*D*U.

       B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
	       On entry, the right hand side vectors B for the system of linear equations.  On exit, the solution vectors, X.

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

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

LAPACK version 3.0						   15 June 2000 							 DPTTRS(l)