Quadruple integral to calculate average distance between two random points within a unit square

quadint.m

% Matlab script to determine average distance between two random points within a unit square

f=@(x,y,z,w) sqrt((x-z).*(x-z) + (y-w).*(y-w)); % Distance Function between points (x,y) and (z,w)

a=0.5;b=0.5;c=0.5;d=0.5; % Integration limits: -a<=x<a -b<=y<b -c<=z<c -d<=w<d

I=integral2(@(x,y)arrayfun(@(x,y)integral2(@(z,w)f(x,y,z,w),-c,c,-d,d),x,y),-a,a,-b,b)

Credit to Daniel F here: https://stackoverflow.com/questions/25141102/quadruple-integral-using-nested-integral2-in-matlab