clarfg.f man page

clarfg.f —

Synopsis

Functions/Subroutines

subroutine clarfg (N, ALPHA, X, INCX, TAU)
CLARFG generates an elementary reflector (Householder matrix).

Function/Subroutine Documentation

subroutine clarfg (integerN, complexALPHA, complex, dimension( * )X, integerINCX, complexTAU)

CLARFG generates an elementary reflector (Householder matrix).

Purpose:

CLARFG generates a complex elementary reflector H of order n, such
that

      H**H * ( alpha ) = ( beta ),   H**H * H = I.
             (   x   )   (   0  )

where alpha and beta are scalars, with beta real, and x is an
(n-1)-element complex vector. H is represented in the form

      H = I - tau * ( 1 ) * ( 1 v**H ) ,
                    ( v )

where tau is a complex scalar and v is a complex (n-1)-element
vector. Note that H is not hermitian.

If the elements of x are all zero and alpha is real, then tau = 0
and H is taken to be the unit matrix.

Otherwise  1 <= real(tau) <= 2  and  abs(tau-1) <= 1 .

Parameters:

N

N is INTEGER
The order of the elementary reflector.

ALPHA

ALPHA is COMPLEX
On entry, the value alpha.
On exit, it is overwritten with the value beta.

X

X is COMPLEX array, dimension
               (1+(N-2)*abs(INCX))
On entry, the vector x.
On exit, it is overwritten with the vector v.

INCX

INCX is INTEGER
The increment between elements of X. INCX > 0.

TAU

TAU is COMPLEX
The value tau.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 107 of file clarfg.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

clarfg(3) is an alias of clarfg.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK