DLAGTM(3)      LAPACK routine of NEC Numeric Library Collection      DLAGTM(3)



NAME
       DLAGTM

SYNOPSIS
       SUBROUTINE DLAGTM (TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX, BETA, B,
           LDB)



PURPOSE
            DLAGTM performs a matrix-vector product of the form

               B := alpha * A * X + beta * B

            where A is a tridiagonal matrix of order N, B and X are N by NRHS
            matrices, and alpha and beta are real scalars, each of which may be
            0., 1., or -1.




ARGUMENTS
           TRANS     (input)
                     TRANS is CHARACTER*1
                     Specifies the operation applied to A.
                     = 'N':  No transpose, B := alpha * A * X + beta * B
                     = 'T':  Transpose,    B := alpha * A'* X + beta * B
                     = 'C':  Conjugate transpose = Transpose

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

           NRHS      (input)
                     NRHS is INTEGER
                     The number of right hand sides, i.e., the number of columns
                     of the matrices X and B.

           ALPHA     (input)
                     ALPHA is DOUBLE PRECISION
                     The scalar alpha.  ALPHA must be 0., 1., or -1.; otherwise,
                     it is assumed to be 0.

           DL        (input)
                     DL is DOUBLE PRECISION array, dimension (N-1)
                     The (n-1) sub-diagonal elements of T.

           D         (input)
                     D is DOUBLE PRECISION array, dimension (N)
                     The diagonal elements of T.

           DU        (input)
                     DU is DOUBLE PRECISION array, dimension (N-1)
                     The (n-1) super-diagonal elements of T.

           X         (input)
                     X is DOUBLE PRECISION array, dimension (LDX,NRHS)
                     The N by NRHS matrix X.

           LDX       (input)
                     LDX is INTEGER
                     The leading dimension of the array X.  LDX >= max(N,1).

           BETA      (input)
                     BETA is DOUBLE PRECISION
                     The scalar beta.  BETA must be 0., 1., or -1.; otherwise,
                     it is assumed to be 1.

           B         (input/output)
                     B is DOUBLE PRECISION array, dimension (LDB,NRHS)
                     On entry, the N by NRHS matrix B.
                     On exit, B is overwritten by the matrix expression
                     B := alpha * A * X + beta * B.

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



LAPACK routine                  31 October 2017                      DLAGTM(3)