SUBROUTINE ZLAGTM( TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX, BETA,
\$                   B, LDB )
*
*  -- LAPACK auxiliary routine (version 3.1) --
*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
*     November 2006
*
*     .. Scalar Arguments ..
CHARACTER          TRANS
INTEGER            LDB, LDX, N, NRHS
DOUBLE PRECISION   ALPHA, BETA
*     ..
*     .. Array Arguments ..
COMPLEX*16         B( LDB, * ), D( * ), DL( * ), DU( * ),
\$                   X( LDX, * )
*     ..
*
*  Purpose
*  =======
*
*  ZLAGTM 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) CHARACTER*1
*          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).
*
*  =====================================================================
*
*     .. Parameters ..
DOUBLE PRECISION   ONE, ZERO
PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
INTEGER            I, J
*     ..
*     .. External Functions ..
LOGICAL            LSAME
EXTERNAL           LSAME
*     ..
*     .. Intrinsic Functions ..
INTRINSIC          DCONJG
*     ..
*     .. Executable Statements ..
*
IF( N.EQ.0 )
\$   RETURN
*
*     Multiply B by BETA if BETA.NE.1.
*
IF( BETA.EQ.ZERO ) THEN
DO 20 J = 1, NRHS
DO 10 I = 1, N
B( I, J ) = ZERO
10       CONTINUE
20    CONTINUE
ELSE IF( BETA.EQ.-ONE ) THEN
DO 40 J = 1, NRHS
DO 30 I = 1, N
B( I, J ) = -B( I, J )
30       CONTINUE
40    CONTINUE
END IF
*
IF( ALPHA.EQ.ONE ) THEN
IF( LSAME( TRANS, 'N' ) ) THEN
*
*           Compute B := B + A*X
*
DO 60 J = 1, NRHS
IF( N.EQ.1 ) THEN
B( 1, J ) = B( 1, J ) + D( 1 )*X( 1, J )
ELSE
B( 1, J ) = B( 1, J ) + D( 1 )*X( 1, J ) +
\$                        DU( 1 )*X( 2, J )
B( N, J ) = B( N, J ) + DL( N-1 )*X( N-1, J ) +
\$                        D( N )*X( N, J )
DO 50 I = 2, N - 1
B( I, J ) = B( I, J ) + DL( I-1 )*X( I-1, J ) +
\$                           D( I )*X( I, J ) + DU( I )*X( I+1, J )
50             CONTINUE
END IF
60       CONTINUE
ELSE IF( LSAME( TRANS, 'T' ) ) THEN
*
*           Compute B := B + A**T * X
*
DO 80 J = 1, NRHS
IF( N.EQ.1 ) THEN
B( 1, J ) = B( 1, J ) + D( 1 )*X( 1, J )
ELSE
B( 1, J ) = B( 1, J ) + D( 1 )*X( 1, J ) +
\$                        DL( 1 )*X( 2, J )
B( N, J ) = B( N, J ) + DU( N-1 )*X( N-1, J ) +
\$                        D( N )*X( N, J )
DO 70 I = 2, N - 1
B( I, J ) = B( I, J ) + DU( I-1 )*X( I-1, J ) +
\$                           D( I )*X( I, J ) + DL( I )*X( I+1, J )
70             CONTINUE
END IF
80       CONTINUE
ELSE IF( LSAME( TRANS, 'C' ) ) THEN
*
*           Compute B := B + A**H * X
*
DO 100 J = 1, NRHS
IF( N.EQ.1 ) THEN
B( 1, J ) = B( 1, J ) + DCONJG( D( 1 ) )*X( 1, J )
ELSE
B( 1, J ) = B( 1, J ) + DCONJG( D( 1 ) )*X( 1, J ) +
\$                        DCONJG( DL( 1 ) )*X( 2, J )
B( N, J ) = B( N, J ) + DCONJG( DU( N-1 ) )*
\$                        X( N-1, J ) + DCONJG( D( N ) )*X( N, J )
DO 90 I = 2, N - 1
B( I, J ) = B( I, J ) + DCONJG( DU( I-1 ) )*
\$                           X( I-1, J ) + DCONJG( D( I ) )*
\$                           X( I, J ) + DCONJG( DL( I ) )*
\$                           X( I+1, J )
90             CONTINUE
END IF
100       CONTINUE
END IF
ELSE IF( ALPHA.EQ.-ONE ) THEN
IF( LSAME( TRANS, 'N' ) ) THEN
*
*           Compute B := B - A*X
*
DO 120 J = 1, NRHS
IF( N.EQ.1 ) THEN
B( 1, J ) = B( 1, J ) - D( 1 )*X( 1, J )
ELSE
B( 1, J ) = B( 1, J ) - D( 1 )*X( 1, J ) -
\$                        DU( 1 )*X( 2, J )
B( N, J ) = B( N, J ) - DL( N-1 )*X( N-1, J ) -
\$                        D( N )*X( N, J )
DO 110 I = 2, N - 1
B( I, J ) = B( I, J ) - DL( I-1 )*X( I-1, J ) -
\$                           D( I )*X( I, J ) - DU( I )*X( I+1, J )
110             CONTINUE
END IF
120       CONTINUE
ELSE IF( LSAME( TRANS, 'T' ) ) THEN
*
*           Compute B := B - A'*X
*
DO 140 J = 1, NRHS
IF( N.EQ.1 ) THEN
B( 1, J ) = B( 1, J ) - D( 1 )*X( 1, J )
ELSE
B( 1, J ) = B( 1, J ) - D( 1 )*X( 1, J ) -
\$                        DL( 1 )*X( 2, J )
B( N, J ) = B( N, J ) - DU( N-1 )*X( N-1, J ) -
\$                        D( N )*X( N, J )
DO 130 I = 2, N - 1
B( I, J ) = B( I, J ) - DU( I-1 )*X( I-1, J ) -
\$                           D( I )*X( I, J ) - DL( I )*X( I+1, J )
130             CONTINUE
END IF
140       CONTINUE
ELSE IF( LSAME( TRANS, 'C' ) ) THEN
*
*           Compute B := B - A'*X
*
DO 160 J = 1, NRHS
IF( N.EQ.1 ) THEN
B( 1, J ) = B( 1, J ) - DCONJG( D( 1 ) )*X( 1, J )
ELSE
B( 1, J ) = B( 1, J ) - DCONJG( D( 1 ) )*X( 1, J ) -
\$                        DCONJG( DL( 1 ) )*X( 2, J )
B( N, J ) = B( N, J ) - DCONJG( DU( N-1 ) )*
\$                        X( N-1, J ) - DCONJG( D( N ) )*X( N, J )
DO 150 I = 2, N - 1
B( I, J ) = B( I, J ) - DCONJG( DU( I-1 ) )*
\$                           X( I-1, J ) - DCONJG( D( I ) )*
\$                           X( I, J ) - DCONJG( DL( I ) )*
\$                           X( I+1, J )
150             CONTINUE
END IF
160       CONTINUE
END IF
END IF
RETURN
*
*     End of ZLAGTM
*
END