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CentOS 7.0 - man page for dlarfg (centos section 3)

dlarfg.f(3)							      LAPACK							       dlarfg.f(3)

dlarfg.f -
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 (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 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: September 2012 Definition at line 107 of file dlarfg.f. Author Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 dlarfg.f(3)