[yt-users] Change in SPH kernel behavior

[Matthew Turk]

Hi all,

I wanted to bring to your attention a change in the SPH smoothing
kernel behavior.  This has landed on the development version on yt,
but *not* the stable, and will not be backported to stable until the
next major release (3.3).

Previously, a kernel normalization was applied to smoothed grid cells.
This could result in mass conservation not being 100% preserved; some
cases were worse than others.  (Cosmology was typically fine.)  The
recent change has removed the normalization step.

Here are some relevant PRs:

https://bitbucket.org/yt_analysis/yt/pull-requests/1740/remove-normalization-from-smoothing-kernel
https://bitbucket.org/yt_analysis/yt/pull-requests/1721/allow-for-neighbors-of-neighbors-searching

-Matt