function bookfig2mesh(a)
% Simple script to generate Figure 2, chapter 14 WITHOUT SPM! Just Matlab
% Book: Human Brain Function. Academic Press, 2nd edition, 2003
% Authors: Frackowiak, Friston, Frith, Dolan, Price, Zeki, Ashburner, and Penny.
% Script source: http://www.poirrier.be/~jean-etienne/presentations/rft/

% !!!!! YOU SHOULD HAVE RUN SCRIPT bookfig1.m BEFORE THIS ONE
% !!!!!!!!!! IN ORDER TO HAVE THE CORRECT AND SAME 'a' MATRIX !

% How to run it? "bookfig2mesh(a);"
% Argument 'a' is the square ramdom map from script bookfig1!

% The DIFFERENCE with bookfig2.m is here: graph = MESH (instead of imagesc)

% Clear screen
clf;
close;

% Compute replacement of random values by the mean within each square
dim = 10; % square dimension --> can be modified for any other dimension
nsquare = 100 / dim; % number of squares in one dimension of image
sum = 0; % sum of values for each square
n = 0; % number of values collected in each square

for i = 1:nsquare
    for j = 1:nsquare
        % traverse each square to collect random data
        for k = ((i - 1) * 10 + 1):((i - 1) * 10 + 10)
            for l = ((j - 1) * 10 + 1):((j - 1) * 10 + 10)
                % get data
                sum = sum + a(k, l);
                n = n + 1;
            end
        end
        mean = sum / n;
        % traverse each square to put means data
        for k = ((i - 1) * 10 + 1):((i - 1) * 10 + 10)
            for l = ((j - 1) * 10 + 1):((j - 1) * 10 + 10)
                % put the mean
                a(k, l) = mean;
            end
        end
        % reset values
        sum = 0;
        n = 0;
    end
end

h = mesh(a);

% Beautify image
set(gca,'YDir','normal');
colormap(gray);
ylabel('Position du pixel en Y');
xlabel('Position du pixel en X');