[yt-users] YTSphereTooSmall

[Matthew Turk]

Hi Geoffrey,

While I think Stephen might know why the difference between
maximum_radius / virial_radius is confusing the system here, I want to
suggest you back up a bit.  Do you really want to analyze halos that
are O(dx) across?

-Matt

On Wed, May 23, 2012 at 7:49 AM, Geoffrey So <gsiisg at gmail.com> wrote:
> I get this behavior when I was trying to compare the sphere stuff with my
> ellipsoid mod, I sometimes get spheres that are bigger than the cell yet
> raise the exception
> YTSphereTooSmall.
>
> In my script I print out the sphere's radius, virial radius
> (halo.maximum_radius(), halo.virial_radius()) and halo number (halo.id), and
> prints out a smaller than cell warning and return 0 for all attributes when
> it raises the YTSphereTooSmall exception:
>
> halo 5 radius 1.5050650880000000e-02 virial radius 1.2055938905417463e-03
> smaller than cell on core 5
> halo 4 has max radius 1.2223814100000001e-02 virial radius
> 5.3953301266098522e-03
> halo 2 has max radius 1.9527046860000001e-02 virial radius
> 4.1620297341626667e-03
> halo 3 has max radius 1.0534633139999999e-02 virial radius
> 5.3662327185065445e-03
> halo 1 has max radius 1.8385822579999999e-02 virial radius
> 4.6616257644500492e-03
> halo 0 has max radius 2.7329332320000000e-02 virial radius
> 6.9309345140911253e-03
>
> Since this is a unigrid run with no AMR, the check in data_objects.py should
> be the same self.hierarchy.get_smallest_dx()
> if radius < self.hierarchy.get_smallest_dx():
>             raise YTSphereTooSmall(pf, radius,
> self.hierarchy.get_smallest_dx())
>
> The resolution is 800 cube so 1/800 dx should be 1.25e-03.  The only thing
> smaller than 1.25e-03 is the virial radius of halo 5, but the halo sphere
> object was obtained using halo.get_sphere() which according to the Doc page
> uses the maximum_radius() by default.  So it looks like the sphere has a
> radius from maximum_radius(), but during the check to see if "radius" is too
> small, it is using the virial radius instead.  Is this something intended?
>
> From
> G.S.
>
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