Docstring of jax.scipy.interpolate.RegularGridInterpolator does not mention extrapolation behavior

[timmens]

Problem Description

In the documentation of scipy's scipy.interpolate.RegularGridInterpolator you can find a sentence on extrapolation in the description of the fill_value argument:

fill_value: float or None, optional

The value to use for points outside of the interpolation domain. If None, values outside the domain are extrapolated.
Default is np.nan.

The documentation of jax.scipy.interpolate.RegularGridInterpolator just states

Parameters:

• ...
• fill_value – value returned for points outside the grid, defaults to NaN.

There is no mention of any extrapolation behavior in JAX's source code either. However, passing fill_value=None to JAX's RegularGridInterpolator results in an extrapolation. (In my tests, it also produces the same results as the scipy function.)

Request

I think this behavior should be listed in the JAX function's docstring. Since this problem concerns only a docstring, I did not want to open an issue, but I can do that or open a PR with a fix if necessary.

[jakevdp]

Seems reasonable, thanks! Would you like to put together a PR with the change?

[timmens]

Yes, I can do that!