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-negative beta.

Function/Subroutine Documentation

subroutine dlarfgp (integer N, double precision ALPHA, double precision, dimension( * ) X, integer INCX, double precision TAU)

DLARFGP generates an elementary reflector (Householder matrix) with non-negative 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:

November 2017

Definition at line 106 of file dlarfgp.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Tue Nov 14 2017 Version 3.8.0 LAPACK