%
% Brownian Motion 
%
% Random Walk, Math Biology, April 11, 2007
% Jae-Hun Jung
%

N =300;
M = zeros(N);

s = 60; md(1:s) = 0.5;
t = 60; mt(1:s) = 1;

p1(1)=N/2; p2(1)=N/2;
q1(1)=N/2; q2(1)=N/2;

for j=2:s
    if mod(j,2)==0
        r = (-1)^(j/2+1);
        h = 0;
    else
        r = 0;
        h = -1;
    end
    p1(j) = p1(j-1)+h;
    p2(j) = p2(j-1)+r;
    M(p1(j),p2(j))=md(j);
    q1(j) = p1(j-1)+h;
    q2(j) = p2(j-1)+r;
    M(q1(j),q2(j))=mt(j);
end
imagesc(M,[0 1])
pause

for i=1:2000
    for j=1:s
    [p1(j) p2(j)] = position(p1(j),p2(j));
    [q1(j) q2(j)] = position2(q1(j),q2(j));
    end
    
    %M = zeros(N);
    for j=1:s
         M(p1(j),p2(j)) = md(j);
         M(q1(j),q2(j)) = mt(j);
    end
    imagesc(M,[0,1])
    pause(0.00003)
end