LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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slarfg.f File Reference

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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).

Download SLARFG + dependencies [TGZ] [ZIP] [TXT]
 SLARFG generates a real elementary reflector H of order n, such

       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

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

 Otherwise  1 <= tau <= 2.
          N is INTEGER
          The order of the elementary reflector.
          ALPHA is REAL
          On entry, the value alpha.
          On exit, it is overwritten with the value beta.
          X is REAL array, dimension
          On entry, the vector x.
          On exit, it is overwritten with the vector v.
          INCX is INTEGER
          The increment between elements of X. INCX > 0.
          TAU is REAL
          The value tau.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
September 2012

Definition at line 107 of file slarfg.f.

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