division by zero problem

I'm running the code

syms a b c
interval = [-3:0.1:3];
a= interval ;
b= interval;
c= interval;
[A,B,C] = meshgrid(a,b,c);

cur = subs(k,{x y z},{A B C});

which k is given by

syms x y z 

f = cos(x) + cos(y) + cos(z);

fx = diff(f,x);
fy = diff(f,y);
fz = diff(f,z);

fxx = diff(fx,x);
fxy = diff(fx,y);
fxz = diff(fx,z);

fyx = diff(fy,x);
fyy = diff(fy,y);
fyz = diff(fy,z);

fzx = diff(fz,x);
fzy = diff(fz,y);
fzz = diff(fz,z);

mat = [fxx fxy fxz fx; fyx fyy fyz fy; fzx fzy fzz fz; fx fy fz 0];
no = det(mat);
de = (fx^2 + fy^2 + fz^2)^2;
k = de/no;

But it turns out that

Error using symengine

Division by zero.

Error in sym/subs>mupadsubs (line 160)

G = mupadmex('symobj::fullsubs',F.s,X2,Y2);

Error in sym/subs (line 145)

G = mupadsubs(F,X,Y);

Error in curvature (line 41)

cur = subs(k,{x y z},{A B C});

Answer 1

[Matt J]

k = matlabFunction(de/no);

[A,B,C] = meshgrid(-3:0.1:3);

cur = k(A,B,C);

[Teerapong Poltue]

Thanks a lot