%  Rounding Error Example
%
%  Ken Jackson    6 Sept. 2007


format long e
   
x = 1.e-13

y = 1. + x - 1.

ry = (y - x) / x

z = 4. + x - 4.

rz = (z - x) / x



% In exact arithmetic, x = y = z, but the computed values are not equal?
% Can you explain why?  In particular, why is the relative error in y
% about -7.99e-4 and the relative error in z about 3.64e-3?