Help with 2d random walk

A particle moving in a sheet where -1<y<1 and 0<x<5. It will start at x=0 and between -0.5<y<0.5. After each step, it will move a distance defined by d=0.2*log(rand()) and a random angle from –pi/4 to pi/4. Plot a sample movement. Find after 1000 iterations how many particles make it to the end of the sheet (ie. X>5).

[per isakson]

homework?

Answer 1

[David Sanchez]

This may be of help:

% Initial position
x = 0;
y = 0;

for k = 1:1000
    %  -1<y<1 and 0<x<5.
     d = 0.2*log(rand);
    %  random angle between –pi/4 to pi/4
    % Generate values from the uniform distribution on the interval [a,b]:
    a = -pi/4;
    b = pi/4;
    r = a + (b-a)*rand;
    % Position:
    x = x + d*cos(r);
    y = y + d*sin(r);
end