dlarz.f(3)

NAME
dlarz.f -

SYNOPSIS

  Functions/Subroutines

subroutine dlarz (SIDE, M, N, L, V, INCV, TAU, C, LDC, WORK)
DLARZ applies an elementary reflector (as returned by stzrzf) to a general matrix.

Function/Subroutine Documentation

  subroutine dlarz (characterSIDE, integerM, integerN, integerL, double precision, dimension( * )V, integerINCV, double precisionTAU, double precision, dimension( ldc, * )C, integerLDC, double precision, dimension( * )WORK)

DLARZ applies an elementary reflector (as returned by stzrzf) to a general matrix.

Purpose:

     DLARZ applies a real elementary reflector H to a real M-by-N
     matrix C, from either the left or the right. H is represented in the
     form

           H = I - tau * v * v**T

     where tau is a real scalar and v is a real vector.

     If tau = 0, then H is taken to be the unit matrix.

     H is a product of k elementary reflectors as returned by DTZRZF.

Parameters:
    SIDE

              SIDE is CHARACTER*1
              = 'L': form  H * C
              = 'R': form  C * H

    M

              M is INTEGER
              The number of rows of the matrix C.

    N

              N is INTEGER
              The number of columns of the matrix C.

    L

              L is INTEGER
              The number of entries of the vector V containing
              the meaningful part of the Householder vectors.
              If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.

    V

              V is DOUBLE PRECISION array, dimension (1+(L-1)*abs(INCV))
              The vector v in the representation of H as returned by
              DTZRZF. V is not used if TAU = 0.

    INCV

              INCV is INTEGER
              The increment between elements of v. INCV <> 0.

    TAU

              TAU is DOUBLE PRECISION
              The value tau in the representation of H.

    C

              C is DOUBLE PRECISION array, dimension (LDC,N)
              On entry, the M-by-N matrix C.
              On exit, C is overwritten by the matrix H * C if SIDE = 'L',
              or C * H if SIDE = 'R'.

    LDC

              LDC is INTEGER
              The leading dimension of the array C. LDC >= max(1,M).

    WORK

              WORK is DOUBLE PRECISION array, dimension
                             (N) if SIDE = 'L'
                          or (M) if SIDE = 'R'

Author:
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Date:
    September 2012

Contributors:
    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

Further Details:

Definition at line 146 of file dlarz.f.

Author

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