clear; close all
%
%  Like problem 29, p. 215
%
x = 0;
y = 0;
b = 2;
ds = b/50;
h = plot(x,y,'*r');
xlim([-b b]); ylim([-b b]); grid
%axis equal
%set(gca,'XTick',[],'YTick',[])
hold on
rx = randn(10000,1);
ry = randn(10000,1);
n = 0;
while abs(x) < b & abs(y) < b
    n = n+1;
    x = x + ds*rx(n);
    y = y + ds*ry(n);
    set(h,'XData',x,'YData',y);
    pause(0.02)
end
title(sprintf('%d steps',n));