function PI=GA_f631(x)
global MIN_offset MUL_factor Emin MDL
global FT Se Sde Su ex631f
% Fitness function evaluation of Example 6.3-1.

% PenChen Chou, 8-4-2001

Se=GA_round4dp(x(1));
Sde=GA_round4dp(x(2));
Su=GA_round4dp(x(3));

% Get Y
[t, X, Y]=sim(MDL,[0:0.01:FT]);
I=find(t>0.02);
error=abs(Y(:,1)); error=error(I);
ERR=1000*sum(error);
PI=ERR;
if MIN_offset>0
   PI=MIN_offset-PI;
   if PI<0, PI=10; end;
end;
if Emin>ERR
   Emin=ERR; fprintf('\nERR=%f',ERR);
   %save ex622_data Se Sde Su ERR
   %pause(2)
else
   fprintf('>'); 
end;