Added normalized_epsilon as a parameter to convolve_fft

[samverstocken]

This allows the user of convolve_fft to choose the upper limit of deviation between the kernel sum and unity, so that it can for example be adjusted for the specific floating-point precision of the kernel array

[pllim]

Add `` around normalize_kernel to mark it as another keyword.

[MSeifert04]

Also if a parameter is optional it is custom to provide or hint at the default value. Something like Default is "1e-8". (or defaults to xxx, ...)

Another thing that could be added is a sphinx directive when the parameter was added, something like: .. versionadded:: 1.3 (or 1.2.x).

This reminds me: This PR needs a Changelog entry (home directory /Changes.rst) for the appropriate version/subpackage under "API changes" (or "New features").

[pllim]

This is more of an API change.

[pllim]

This looks uncontroversial enough to me, but let's see what the sub-package maintainer(s) say. Still needs a change log.

[MSeifert04]

I'm not sure if it's appropriate here but numpy has a finfo() function to get the smallest epsilon:

import numpy as np

def get_epsilon(arr):
    return np.finfo(arr.dtype).eps

>>> get_epsilon(np.array([1,2,3], dtype=np.float32))
1.1920929e-07
>>> get_epsilon(np.array([1,2,3], dtype=np.float64))
2.2204460492503131e-16

But that's only the minimal epsilon for the number 1, but it could provide at least an order of magnitude estimate.

[samverstocken]

@MSeifert04 Thanks for showing that finfo() function, good to know.
@pllim @MSeifert04 I will try to improve the PR with your suggestions.

[MSeifert04]

This line contains a trailing whitespace (at the end of the line). That's why your first build failied during the PEP-8 check.

[eteq]

Pushing this to 2.0 as it appears @astrofrog's comments have not yet been resolved and the branch has conflits.

[samverstocken]

I'm sorry but I currently don't have the time to look at his again.. Alas, not paid to do programming..

[pllim]

Is anyone interested to take over? If not, I guess we can close this.

[mwcraig]

Seems pretty close to done, I could work on it Monday. May have to open a new PR with these changes cherry-picked if a force push doesn't work....

[mwcraig]

Closing in favor of #5649, which is this rebased, and with the comments made here addessed.