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## zlarz()

subroutine zlarz | ( | character | side,
|  | integer | m,
|  | integer | n,
|  | integer | l,
|  | complex*16, dimension( * ) | v,
|  | integer | incv,
|  | complex*16 | tau,
|  | complex*16, dimension( ldc, * ) | c,
|  | integer | ldc,
|  | complex*16, dimension( * ) | work )

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

Download ZLARZ + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> ZLARZ applies a complex elementary reflector H to a complex
      !> M-by-N matrix C, from either the left or the right. H is represented
      !> in the form
      !>
      !>       H = I - tau * v * v**H
      !>
      !> where tau is a complex scalar and v is a complex vector.
      !>
      !> If tau = 0, then H is taken to be the unit matrix.
      !>
      !> To apply H**H (the conjugate transpose of H), supply conjg(tau) instead
      !> tau.
      !>
      !> H is a product of k elementary reflectors as returned by ZTZRZF.
      !>

Parameters

  [in]

  SIDE

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

  [in]

  M

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

  [in]

  N

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

  [in]

  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.
      !>

  [in]

  V

      !>          V is COMPLEX*16 array, dimension (1+(L-1)*abs(INCV))
      !>          The vector v in the representation of H as returned by
      !>          ZTZRZF. V is not used if TAU = 0.
      !>

  [in]

  INCV

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

  [in]

  TAU

      !>          TAU is COMPLEX*16
      !>          The value tau in the representation of H.
      !>

  [in,out]

  C

      !>          C is COMPLEX*16 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'.
      !>

  [in]

  LDC

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

  [out]

  WORK

      !>          WORK is COMPLEX*16 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.

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

Further Details:

      !>