tt = Flatten[Table[{x, y, z, btot[x, y, z]}, {x, -1, 1, 0.1}, {y, -1, 1,0.1}, {z, -1, 1, 0.1}], 2];
ff = Interpolation[tt]
Till here it is working fine as it is returning the values of the interpolated function at various {x,y,z}
points.
Then I want to find the gradient of this interpolated function. But when I am using
ffd[x_,y_,z_]:= D[ff[x,y,z],{{x,y,z}}]
I am not getting the gradient.
:=
in your code with=
and it should work $\endgroup$:=
with=
. $\endgroup$Remove[ffd]
before trying with=
. $\endgroup$