If I read the mean curvature formula H(A)
correctly then you mistreated it; there is z=f(u,v)
and f
is a scalar function, not a vector function as you specified. I remark this because you use the exponent 3/2
in the denominator which is correct for the special case z = f(u,v)
only. In general the definition is
H[A] := 1/2 ((L G - 2 M F + N E)/(E G - F^2))