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| SRC/lapack_64_obj/dlarz.f(3) | Library Functions Manual | SRC/lapack_64_obj/dlarz.f(3) | 
NAME¶
SRC/lapack_64_obj/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 (character side, integer m, integer n, integer l, double precision, dimension( * ) v, integer incv, double precision tau, double precision, dimension( ldc, * ) c, integer ldc, 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.
Contributors:
A. Petitet, Computer Science Dept., Univ. of Tenn.,
  Knoxville, USA
Further Details:
!>
Definition at line 145 of file dlarz.f.
Author¶
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