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NAME
     zlagtm - 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 ZLAGTM( TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX,
               BETA, B, LDB )

     CHARACTER TRANS

     INTEGER LDB, LDX, N, NRHS

     DOUBLE PRECISION ALPHA, BETA

     COMPLEX*16 B( LDB, * ), D( * ), DL( * ), DU( * ), X( LDX,  *
               )



     #include <sunperf.h>

     void zlagtm(char trans, int n, int nrhs, double alpha, doub-
               lecomplex  *dl,  doublecomplex  *d,  doublecomplex
               *du, doublecomplex *zx,  int  ldx,  double  dbeta,
               doublecomplex *zb, int ldb) ;

PURPOSE
     ZLAGTM 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**T * X + beta
               * B
               = 'C':  Conjugate transpose, B := alpha * A**H * X
               + beta * B

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

     DL        (input) COMPLEX*16 array, dimension (N-1)
               The (n-1) sub-diagonal elements of T.

     D         (input) COMPLEX*16 array, dimension (N)
               The diagonal elements of T.

     DU        (input) COMPLEX*16 array, dimension (N-1)
               The (n-1) super-diagonal elements of T.

     X         (input) COMPLEX*16 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) DOUBLE PRECISION
               The scalar beta.  BETA must be  0.,  1.,  or  -1.;
               otherwise, it is assumed to be 1.

     B         (input/output)   COMPLEX*16    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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