zlarz.f man page

zlarz.f —



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

Function/Subroutine Documentation

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.  


 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

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


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


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


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


          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 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.


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


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


          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'.


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


          WORK is COMPLEX*16 array, dimension
                         (N) if SIDE = 'L'
                      or (M) if SIDE = 'R'

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.


December 2016


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

Further Details:

Definition at line 149 of file zlarz.f.


Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page zlarz(3) is an alias of zlarz.f(3).

Sat Jun 24 2017 Version 3.7.1 LAPACK