// given a function in the univariate form, returns true if PN and false otherwise
function IsPN(poly)
R<x>:=Parent(f);
F<w>:=BaseRing(R);
n:=Degree(F); p:=Characteristic(F);
    f:= func< x| Evaluate(poly, x)>;
    for i in {0..p^n-2} do
        a:=w^i;
        set_b := {};
        for y in FiniteField(p,n) do
            b:=f(y+a)-f(y);
            if b notin set_b then
                Include(~set_b,b);
            else
                return false;
            end if;
        end for;
    end for; 
    return true;
end function;