Previous: clarfb Up: ../lapack-c.html Next: clarft
NAME CLARFG - generate a complex elementary reflector H of order n, such that H' * ( alpha ) = ( beta ), H' * H = I SYNOPSIS SUBROUTINE CLARFG( N, ALPHA, X, INCX, TAU ) INTEGER INCX, N COMPLEX ALPHA, TAU COMPLEX X( * ) PURPOSE CLARFG generates a complex elementary reflector H of order n, such that ( x ) ( 0 ) where alpha and beta are scalars, with beta real, and x is an (n-1)-element complex vector. H is represented in the form H = I - tau * ( 1 ) * ( 1 v' ) , ( v ) where tau is a complex scalar and v is a complex (n-1)- element vector. Note that H is not hermitian. If the elements of x are all zero and alpha is real, then tau = 0 and H is taken to be the unit matrix. Otherwise 1 <= real(tau) <= 2 and abs(tau-1) <= 1 . ARGUMENTS N (input) INTEGER The order of the elementary reflector. ALPHA (input/output) COMPLEX On entry, the value alpha. On exit, it is overwrit- ten with the value beta. X (input/output) COMPLEX array, dimension (1+(N-2)*abs(INCX)) On entry, the vector x. On exit, it is overwritten with the vector v. INCX (input) INTEGER The increment between elements of X. INCX <> 0. TAU (output) COMPLEX The value tau.