dlarfgp.f man page

dlarfgp.f —

Synopsis

Functions/Subroutines

subroutine dlarfgp (N, ALPHA, X, INCX, TAU)
DLARFGP generates an elementary reflector (Householder matrix) with non-negatibe beta.

Function/Subroutine Documentation

subroutine dlarfgp (integerN, double precisionALPHA, double precision, dimension( * )X, integerINCX, double precisionTAU)

DLARFGP generates an elementary reflector (Householder matrix) with non-negatibe beta.

Purpose:

DLARFGP generates a real elementary reflector H of order n, such
that

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

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

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

where tau is a real scalar and v is a real (n-1)-element
vector.

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

Parameters:

N

N is INTEGER
The order of the elementary reflector.

ALPHA

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

X

X is DOUBLE PRECISION 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 DOUBLE PRECISION
The value tau.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 105 of file dlarfgp.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK