How to use ezplot ?

I typed this but nothing shows up

syms x1 x2
f(x1, x2) = x1^2 + 9*x2^2;
ezplot(f);

Answer 1

[Star Strider]

For a function of two variables, use the ezsurf (or preferably fsurf) function instead:

syms x1 x2
f(x1, x2) = x1^2 + 9*x2^2;
ezsurf(f)

or:

syms x1 x2
f(x1, x2) = x1^2 + 9*x2^2;
fsurf(f)