% explore_eps22.m
% k. stewart spring 1998 - written for CS 205
% we want to examine the behavior of the floating point
% number system
%** updated to write nicely formatted output to a file
%*********************************************************
%
% assuming no background or familiarity with floating point
% behavior, we'll examine first a finite list of values
%
% it's dangerous to use the variable named "eps" since this is
% predefined MATLAB value which the user can reset
%
echo off
u = 1/2^15; % start the search off at an arbitrary, but exact, binary value
formax = 40;
for i=1:formax
    if (1.0 + u > 1.0) ;
        fprintf('explore_eps2.out','For u = %12.8g \t 1.0+u> 1.0 \n',u)
    else
        fprintf('explore_eps2.out',...
		'Finally, after %4.0f iterations we find that\n',i)
        fprintf('explore_eps2.out',...
		'  for u = %12.8g 1.0+u is NOT > 1.0 \n',u)
        fprintf('explore_eps2.out',...
		'  therefore unit roundoff is %12.8g\n',2*u)
        fprintf('explore_eps2.out',...
		'  Break out of the for loop\n')
        break;
    end % if-else block
    u = u/2;

    if (i == formax) 
         fprintf('explore_eps2.out',...
		'Used %g loop iterations without finding u\n',formax)
    end

end % for i=1:10 loop