[yt-users] YTSphereTooSmall

Geoffrey So gsiisg at gmail.com
Wed May 23 13:40:16 PDT 2012


Stephen,

I'm printing the warning message when along with the halo.id as the
exception is raised, so it appears that halo 5 in this case has a radius
smaller than dx, but what it really should be checking is the maximum
instead of the virial radius instead if I'm not mistaken.

Matt,

I just want the field attributes of where the halo is located, and I'm
comparing the attributes to the region surrounding the halo (up to 3x the
virial or maximum radius) to see if there's anything that is substantially
different.  I want to see what's different in the field quantity that
suppresses star formation in lower mass haloes.  In this analysis the
detailed shape and size of the sphere doesn't really matter, I'm just using
it as a data container.

Right now I'm trying to output Density averaged values of each halo but
whenever I encounter a halo with radius smaller than a cell (triggering
YTSphereTooSmall), I output 0 for all attributes.  So I expect lots of
zeros to occur on the small end.  However I'm seeing some zeros scattered
even in the high mass end with large maximum radius, and I think the high
mass halos with zeros is the result of it having a small virial radius, at
least that's my current hypothesis.

I'm going to try to go down the list from the high mass end to see if the
second halo giving me zeros on the high end also have a virial radius
smaller than dx.

I guess a work around for this problem temporarily is to
use pf.h.sphere(halo.center_of_mass(), halo.maximum_radius()) instead of
calling halo.get_sphere().

From
G.S.

On Tue, May 22, 2012 at 6:16 PM, Stephen Skory <s at skory.us> wrote:

> Hi Geoffrey and Matt,
>
> > While I think Stephen might know why the difference between
> > maximum_radius / virial_radius is confusing the system here,
>
> I don't quite know what's going on. halo.get_sphere() should give you
> a YT sphere centered on the center of mass of the halo, with radius of
> .maximum_radius(). Perhaps it's not halo 5 that's giving you the
> error? Or there's an error in what you're printing?
>
> > I want to
> > suggest you back up a bit.  Do you really want to analyze halos that
> > are O(dx) across?
>
> I agree with Matt that you should take a close look at what you are
> asking from these halos, and if one or just a few cells are sufficient
> to give you that.
>
> --
> Stephen Skory
> s at skory.us
> http://stephenskory.com/
> 510.621.3687 (google voice)
> _______________________________________________
> yt-users mailing list
> yt-users at lists.spacepope.org
> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>
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