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slagtm

 NAME
      SLAGTM - perform 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

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

          CHARACTER      TRANS

          INTEGER        LDB, LDX, N, NRHS

          REAL           ALPHA, BETA

          REAL           B( LDB, * ), D( * ), DL( * ), DU( * ), X(
                         LDX, * )

 PURPOSE
      SLAGTM performs a matrix-vector product of the form

 ARGUMENTS
      TRANS   (input) CHARACTER
              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) 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 matrices X and B.

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

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

      D       (input) REAL array, dimension (N)
              The diagonal elements of T.

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

      X       (input) REAL array, dimension (LDX,NRHS)
              The N by NRHS matrix X.  LDX     (input) INTEGER The

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

      BETA    (input) REAL
              The scalar beta.  BETA must be 0., 1., or -1.; oth-
              erwise, it is assumed to be 1.

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