zlagtm(3S)

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
     0., 1., or -1

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, * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

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
             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).

SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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