slarfg.f - Man Page

SRC/slarfg.f

Synopsis

Functions/Subroutines

subroutine slarfg (n, alpha, x, incx, tau)
SLARFG generates an elementary reflector (Householder matrix).

Function/Subroutine Documentation

subroutine slarfg (integer n, real alpha, real, dimension( * ) x, integer incx, real tau)

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.

Definition at line 105 of file slarfg.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK