% Problem # 20 (or Richard Brent's Function # 2)
% Range of initial points: -10 <= x <= 10
% Global maxima: x=1.195136633593035
% f(x)=0.063490528936440
% Coded by: Ali R. Alroomi | Last Update: 25 Feb. 2015 | www.al-roomi.org

clear
clc
warning off

xmin=-10;
xmax=10;
R=100000; % steps resolution
x=xmin:(xmax-xmin)/R:xmax;

for i=1:length(x)
    f(i)=(x(i)-sin(x(i)))*exp(-x(i)^2);
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');