[yt-users] different hydrogen densities from different versions of yt

[Lauren Corlies]

Hello,

I've been a yt user for a while now but have recently noticed something
concerning. A few months ago, I made the switch to yt3 and am currently
using the new yt 3.3.4

I've been working with recently generated, cosmological zoom in simulations
and I've generated a basic yt ray object.  When I plot the hydrogen number
density along the ray, the values that it's generating are un-physically
low (seen here <http://i.imgur.com/1C1oAVr.png>).

It's especially concerning because when I use the old yt2 installation:
Version = 2.7-dev
Changeset = 1f9ca06815d0

and generate a yt ray object with the exact same trajectory, the hydrogen
number density values are much more sensible (seen here
<http://i.imgur.com/tcDcNd8.png>). The rays in both yt versions have mostly
the same shape but there are some strong features in the yt2 version than
in the yt3 one.

The discrepancy is specifically with this field and not other intrinsic
fields like temperature or regular density (also attached).

Am I accessing the field incorrectly and there's a better way to get these
values with the new version of yt? Or is there something deeper happening?
The hydrogen number density is particularly important for the ion densities
and emission that I've been interested in.

All of the plots and the script <http://paste.yt-project.org/show/7066/> to
generate them are attached and posted online as described on the docs page,
tagged with my last name with links included as an attachment.

Thanks for the help,
Lauren Corlies
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