% Bird-Like Function
% Range of initial points: -4 <= x <= 4
% One global minima: x=2 and two global maxima: x={-1,1}
% fmin(x)=2 and fmax(x)=2.5
% Coded by: Ali R. Alroomi | Last Update: 17 May 2015 | www.al-roomi.org
 
clear
clc
warning off
 
xmin=-4;
xmax=4;
R=100000; % steps resolution
x=xmin:(xmax-xmin)/R:xmax;
 
for i=1:length(x)
    f(i)=(2*x(i)^4+x(i)^2+2)/(x(i)^4+1);
end
 
plot(x,f,'r','LineWidth',2);grid;set(gca,'FontSize',12);axis([-4 4 -0.5 3.5]);
xlabel('x','FontName','Times','FontSize',20,'FontAngle','italic');
ylabel('f(x)','FontName','Times','FontSize',20,'FontAngle','italic');