[SciPy-Dev] backwards-incompatible change in Akima1DInterpolator?

[Andreas Hilboll]

Currently, interpolate.Akima1DInterpolator does not use Ppoly's
``extrapolate`` kwarg, but always sets ``extrapolate=False``.

I would like to expose the extrapolation feature in the API of
Akima1DInterpolator.  However, Ppoly's default value for extrapolate is
True.

So there are two choices:

a. Make Akima1DInterpolator's extrapolate default to False.  This is
backward-compatible, but inconsistent with the usual Ppoly behaviour.

b. Make Akima1DInterpolator's extrapolate default to True.  This is
consistent with Ppoly, but is not backwards-compatible.

One way to go could be add a DeprecationWarning or similar now for 0.17,
and then only expose the extrapolate kwarg in 0.18.

Any opinions on how to attack this issue?

-- Andreas.