im constantly getting this error in my matlab code can someone expalin what i should do or how it should be

• Variable q4 must be of data type sym. It is currently of type symfun. Check where the variable is assigned a value.

syms x y
g(x,y)=x*y/(x^2+y^2);
fyxx=diff(diff(diff(g,y),x),x);
point=[1.2,3.8];
q4=subs(fyxx,{x,y},point);

[lateef]

The original question is assign g(x,y)=xy/x^2+y^2 and calculate Fyxx(1.2,3.8) (triple derivative!) and assign the result to q4.

Answer 1

[Walter Roberson]

q4 = subs(fyxx(x, y), [x,y], point);