I'm quite embrassed for asking this, but these year we had two extra lessons at the uni about matlab... my prof said, that we don't need to participate, but now we have a homework, that we're required to do... T.T

so i have this:

function elli(fun,a,n)

%

if n<4

disp('Legyen n>3')

return

end

if a<= 0

disp('legyen a>0')

return

end

x=linspace(-a,a,n);

[xx,yy]=meshgrid(x);

A=feval(fun,xx,yy);

B=zeros(n,n);

aa=a*a;

for i=1:n

xixxi=x(i)*x(i);

for j=1:n

if xixxi+x(j)*x(j)>aa

A(i,j)=NaN; B(i,j)=NaN;

end

end

end

mesh(B);

hold on

mesh(A)

hold off

and i would have to explain, what this "elli" does...

I would be really greatful for your help...