dlarfg (3)  Linux Man Pages
NAME
dlarfg.f 
SYNOPSIS
Functions/Subroutines
subroutine dlarfg (N, ALPHA, X, INCX, TAU)
DLARFG generates an elementary reflector (Householder matrix).
Function/Subroutine Documentation
subroutine dlarfg (integerN, double precisionALPHA, double precision, dimension( * )X, integerINCX, double precisionTAU)
DLARFG generates an elementary reflector (Householder matrix).
Purpose:

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.
Parameters:

N
N is INTEGER The order of the elementary reflector.
ALPHAALPHA is DOUBLE PRECISION On entry, the value alpha. On exit, it is overwritten with the value beta.
XX is DOUBLE PRECISION array, dimension (1+(N2)*abs(INCX)) On entry, the vector x. On exit, it is overwritten with the vector v.
INCXINCX is INTEGER The increment between elements of X. INCX > 0.
TAUTAU is DOUBLE PRECISION 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 dlarfg.f.
Author
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