clc;
clear all;
close all;

x1=-2;
x2=2;
nx=20;
y1=-2;
y2=2;
ny=20;



x = x1 : (x2-x1)/(nx-1) : x2;
y = y1 : (y2-y1)/(ny-1) : y2;

[X,Y] = meshgrid(x,y);

Z=zeros(nx,ny);

for i=1:nx
    for j=1:ny
        Z(i,j)=banana(x(i),y(j));
    end
end
%Z = X.*Y.*exp(-X.^2-Y.^2);

% pointwise multiplication works now because X and Y are matrices

figure(1)
hold on
contour(X,Y,Z,100);
plot(0.5*(x1+2),0.5*(x1+2),'-ko')
hold off