http://projects.scipy.org/scipy/ticket/1181 the dtypes in kde evaluate only makes sense if we have at least float integer input produces nonsense evaluate has points = atleast_2d(points).astype(self.dataset.dtype) .... result = zeros((m,), points.dtype) .... result += exp(-energy) I don't know which dtypes kde is supposed to handle, but what's the best way to guarantee that the result is "atleast_float", so that a probability makes sense. I don't know what a complex probability is, but handling complex is useful for complex derivatives. Thanks, Josef