clear all; close all;
N = 201;	%generate a 201 by 201 array of points
x=0:(1/(N-1)):1; y=x;	% x and y values between 0 and +1 spaced by % 0.005 (201 values)

r = 0.2;			%set the r parameter

[X,Y]=meshgrid(x,y);	% generate 2D grids of xy values (201 by 201 arrays) X(i,j) = x(j) and Y(i,j) = y(i)

Z=exp(-((X-0.5).^2+(Y-0.5).^2)/(2*r^2));   % generate the Gaussian function on the grid

v=0:.1:1.;	% contours will be from 0 to 1 in steps of 0.1
[C,h]=contour(X,Y,Z,v); % generate the contour plot, including values to label contours
axis square	%make the plot square
clabel(C,h)	%label the contours
xlabel('x (ph)'), ylabel('y (ph)');
set(gca,'ydir','reverse'); 
set(gca,'XAxisLocation','top');      %Xaxis labels on top
colormap([0 0 0]);     % use black only
figure, imshow(Z)