Calling Program from Advanced Graphing

[Tugdual]

Is there a way to call functions from advanced graphing app?
I created a very simple program:

Code:


EXPORT func(X, Y)
BEGIN
return X^2+Y^2;
END;

From the Function App I can call func(X,X) and see a plot
From the Advanced Graphing App if I enter func(X,Y)<=4 I get "Error: Invalid object"

Why the Prime is not consistent?