LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  dlarfg (N, ALPHA, X, INCX, TAU) 
DLARFG generates an elementary reflector (Householder matrix). 
subroutine dlarfg  (  integer  N, 
double precision  ALPHA,  
double precision, dimension( * )  X,  
integer  INCX,  
double precision  TAU  
) 
DLARFG generates an elementary reflector (Householder matrix).
Download DLARFG + dependencies [TGZ] [ZIP] [TXT]DLARFG 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 (n1)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 (n1)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.
[in]  N  N is INTEGER The order of the elementary reflector. 
[in,out]  ALPHA  ALPHA is DOUBLE PRECISION On entry, the value alpha. On exit, it is overwritten with the value beta. 
[in,out]  X  X is DOUBLE PRECISION array, dimension (1+(N2)*abs(INCX)) On entry, the vector x. On exit, it is overwritten with the vector v. 
[in]  INCX  INCX is INTEGER The increment between elements of X. INCX > 0. 
[out]  TAU  TAU is DOUBLE PRECISION The value tau. 
Definition at line 107 of file dlarfg.f.