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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 zero, one, or minus
     one

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, * )



     #include <sunperf.h>

     void slagtm(char trans, int n, int nrhs, float alpha,  float
               *dl,  float  *d,  float  *du,  float *sx, int ldx,
               float sbeta, float *sb, int ldb) ;

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.;
               otherwise, 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).

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