title: How should I get derivatives from scipy RBFInterpolator? (simply, as with bisplev)
body: <p>Question about <a href="https://docs.scipy.org/doc/scipy/reference/generated/scipy.interpolate.RBFInterpolator.html#scipy-interpolate-rbfinterpolator" rel="nofollow noreferrer">scipy.interpolate.RBFInterpolator</a></p>
  <p>I've found RBF gives much smoother 2D interpolation results than B-Splines via <a href="https://docs.scipy.org/doc/scipy/reference/generated/scipy.interpolate.bisplrep.html#scipy-interpolate-bisplrep" rel="nofollow noreferrer">scipy.interpolate.bisplref</a> with my particular data, but I need to take derivatives of what I get. When I evaluate the B-Splines using <a href="https://docs.scipy.org/doc/scipy/reference/generated/scipy.interpolate.bisplev.html#scipy-interpolate-bisplev" rel="nofollow noreferrer">scipy.interpolate.bisplev</a>, I can specify dx and dy to get any order of derivative in each dimention. Is there a similar sort of thing for RBFInterpolator that I'm just not seeing in the documentation? Or should I just take the gradient of the evaluated spline w/ numpy.gradient?</p>