[Yt-dev] HaloProfiler vs. enzo_anyl

[Greg Bryan]

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