slarfg.f man page

slarfg.f —

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine slarfg (integerN, realALPHA, real, dimension( * )X, integerINCX, realTAU)

SLARFG generates an elementary reflector (Householder matrix).

Purpose:

SLARFG 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, 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.

Otherwise  1 <= tau <= 2.

Parameters:

N

N is INTEGER
The order of the elementary reflector.

ALPHA

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

X

X is REAL 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 REAL
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 slarfg.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK