% Problem # 19 (or Lévy-Gomez's Function)
% Range of initial points: 0 <= x <= 6.5
% Two global maxima: x=5.872865514594919
% f(x)=7.815674542981392
% Coded by: Ali R. Alroomi | Last Update: 08 July 2015 | www.al-roomi.org
 
clear
clc
warning off
 
xmin=0;
xmax=6.5;
R=100000; % steps resolution
x=xmin:(xmax-xmin)/R:xmax;
 
for i=1:length(x)
    f(i)=x(i)-sin(3*x(i))+1;
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');