CXML
        	    
LAPACK version 3.0
dgtsv(3)

PURPOSE
  DGTSV - solve the equation  A*X = B,

SYNTAX
  SUBROUTINE DGTSV( N, NRHS, DL, D, DU, B, LDB, INFO )

      INTEGER	    INFO, LDB, N, NRHS

      DOUBLE	    PRECISION B( LDB, * ), D( * ), DL( * ), DU( * )

DESCRIPTION
  DGTSV 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) DOUBLE PRECISION 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-2) elements of the second
	  super-diagonal of the upper triangular matrix U from the LU
	  factorization of A, in DL(1), ..., DL(n-2).

  D	  (input/output) DOUBLE PRECISION 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) DOUBLE PRECISION 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.

  B	  (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
	  On entry, the N by NRHS matrix of 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.