hello
according to the equations given here , the coding is quite simple :
% The epitrochoid with R = 3, r = 1 and d = 1/2
R = 3;
r = 1;
d = 1/2;
theta = linspace(0,2*pi,100);
x = (R+r)*cos(theta) - d*cos((R+r)/r.*theta);
y = (R+r)*sin(theta) - d*sin((R+r)/r.*theta);
plot(x,y);
axis square
