% Dixon-Szego's Function
% Range of initial points: -5 <= x <= 5
% Two global minimum: x={0,2}
% f(x)=0
% Coded by: Ali R. Alroomi | Last Update: 10 August 2015 | www.al-roomi.org
 
clear
clc
warning off
 
xmin=-5;
xmax=5;
R=100000; % steps resolution
x=xmin:(xmax-xmin)/R:xmax;
 
for i=1:length(x)
    f(i)=4*x(i).^2-4*x(i).^3+x(i).^4;
end
 
plot(x,f,'r','LineWidth',2);grid;set(gca,'FontSize',12);
xlabel('x','FontName','Times','FontSize',20,'FontAngle','italic');
ylabel('f(x)','FontName','Times','FontSize',20,'FontAngle','italic');