[Yt-dev] HaloProfiler vs. enzo_anyl
Greg Bryan
gbryan at astro.columbia.edu
Tue Apr 19 20:05:33 PDT 2011
Thanks everyone for working on this functionality.
On Apr 19, 2011, at 2:49 PM, Matthew Turk wrote:
> Hi Britton and John,
>
> John: Thanks very much for adding that to enzo! This will be hugely helpful.
>
> On Mon, Apr 18, 2011 at 3:52 PM, Britton Smith <brittonsmith at gmail.com> wrote:
>> Hi Matt,
>>
>> Thanks for checking into this. This looks like another thing that could be
>> checked off our list with a code sprint. I won't be available for that this
>> week, but could do it next week.
>>
>> Here are some questions that I think we need to consider. While we are not
>> only looking to provide full coverage for all of enzo_anyl's functionality
>> so we can mothball it, we should also be thinking about things that could be
>> improved from enzo_anyl.
>>
>> 1. The density units in enzo_anyl are Msun/Mpc^3. Do we want to keep
>> these? I always converted to cgs back when I used enzo_anyl.
>
> I prefer cgs, but that's because I'm biased. Someone else should answer this.
I think cgs is good (actually SI would be better -- I think astronomy is headed toward convergence with the rest of the scientific world, and we will, in time, also adopt SI).
>
>>
>> 2. Stuff like clumping factors and velocity dispersion will require some
>> additional functionality out of profiles. It's currently not easy to get
>> means and standard deviations in individual bins for profiles. Does anyone
>> have any idea how difficult it would be to implement this functionality?
>
> Means I think are not too hard, but standard deviation is trickier.
> David and I talked about this a while back.
I would think standard deviation is no more difficult than mean. It can be computed in one pass since <(x-<x>)^2> = <x^2> - <x>^2. Although I may just be missing the issue.
Greg
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