% Problem # 7 (Strongin-Zilinskas-Shaltyanis' or Timonov's Function # 2)
% Range of initial points: 3 <= x <= 7.5
% Global maxima: x=5.199778366858
% f(x)=1.601307546494396
% Coded by: Ali R. Alroomi | Last Update: 14 Feb. 2015 | www.al-roomi.org
 
clear
clc
warning off
 
xmin=3;
xmax=7.5;
R=100000; % steps resolution
x=xmin:(xmax-xmin)/R:xmax; 
 
for i=1:length(x)
    f(i)=-sin(x(i))-sin(10*x(i)/3)-log(x(i))+0.84*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');