% Problem # 22
% Range of initial points: 0 <= x <= 20
% Global minima: x=9*pi/2
% f(x)=exp(-27*pi/2)-1
% Coded by: Ali R. Alroomi | Last Update: 17 May 2015 | www.al-roomi.org
 
clear
clc
warning off
 
xmin=0;
xmax=20;
R=100000; % steps resolution
x=xmin:(xmax-xmin)/R:xmax;
 
for i=1:length(x)
    f(i)=exp(-3*x(i))-(sin(x(i)))^3;
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');