% Random walk (simple)
% January 2021 by AG.

itests = 5000;
rng('shuffle')      % use seed as current time

fprintf('Simple random walk \n');
fprintf('iTests = %5i \n', itests);
%fileID = fopen('random2.txt','w');

% First loop - number of steps
for isteps=0:10:200
dav=0.0;
% Second loop - number of tests
for it=1:itests
   x=0;
   y=0;
   r = randi([0 3],1,isteps);
% Thirst loop - walking isteps   
   for is=1:isteps
       iway= r(is);
       switch iway
           case 0
               x = x + 1;
           case 1
               x = x - 1;
           case 2
               y = y + 1;
           case 3
               y = y - 1;
       end
   end %exnd loop 3
   d = sqrt(x*x +y*y);
   dav = dav + d;
end %end loop 2
dav2 = dav/double(itests);
%fprintf(fileID,'%4i  %10f  \n', isteps, dav2);
fprintf('%4i  %10f  \n', isteps, dav2);
end % end loop 1