SRC/dlagtm.f(3)

NAME
SRC/dlagtm.f

SYNOPSIS

  Functions/Subroutines
subroutine dlagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb)
DLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1.

Function/Subroutine Documentation

  subroutine dlagtm (character trans, integer n, integer nrhs, double precision alpha, double precision, dimension( * ) dl, double precision, dimension( * ) d, double precision, dimension( * ) du, double precision, dimension( ldx, * ) x, integer ldx, double precision beta, double precision, dimension( ldb, * ) b, integer ldb)

DLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1.

Purpose:

     DLAGTM performs a matrix-matrix 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.

Parameters
    TRANS

              TRANS is CHARACTER*1
              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

              N is INTEGER
              The order of the matrix A.  N >= 0.

    NRHS

              NRHS is INTEGER
              The number of right hand sides, i.e., the number of columns
              of the matrices X and B.

    ALPHA

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

    DL

              DL is DOUBLE PRECISION array, dimension (N-1)
              The (n-1) sub-diagonal elements of T.

    D

              D is DOUBLE PRECISION array, dimension (N)
              The diagonal elements of T.

    DU

              DU is DOUBLE PRECISION array, dimension (N-1)
              The (n-1) super-diagonal elements of T.

    X

              X is DOUBLE PRECISION array, dimension (LDX,NRHS)
              The N by NRHS matrix X.

    LDX

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

    BETA

              BETA is DOUBLE PRECISION
              The scalar beta.  BETA must be 0., 1., or -1.; otherwise,
              it is assumed to be 1.

    B

              B is DOUBLE PRECISION 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

              LDB is INTEGER
              The leading dimension of the array B.  LDB >= max(N,1).

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 143 of file dlagtm.f.

Author

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