[yt-users] RAMSES units bug in yt-3.0

[Sam Geen]

Hmm, that looks like it should be "mass_unit = rho_u * length_unit**3" 
in line 492. You're right that it mentions the boxlength issue, though.

On 09/05/14 16:50, Matthew Turk wrote:
> Hi Sam,
>
> Okay, sounds good.  Looking at how code unit attributes are set up:
>
> https://bitbucket.org/yt_analysis/yt/src/a14a150c7c81850df81346162bdaff271e77eb50/yt/frontends/ramses/data_structures.py?at=yt-3.0#cl-482
>
> suggests to me that length_unit takes into account boxlen, and
> mass_unit does not.  The comments have some indication why this might
> be.
>
> -Matt
>
> On Fri, May 9, 2014 at 10:46 AM, Sam Geen <samgeen at astro.ox.ac.uk> wrote:
>> Yep; both this and dd["density"] give cgs values that are too small by
>> roughly a factor of boxlen**3.
>>
>> One other thing I need to try is to make sure I'm using the very latest
>> version of YT; I've been playing around with the Ramses frontend so it's
>> possible my version is somehow out of sync. Will let you know if this fixes
>> things.
>>
>>
>> On 09/05/14 16:42, Matthew Turk wrote:
>>> Hi Sam,
>>>
>>> Can you verify the units are in fact incorrect in *cgs*?  Something
>>> like this would work:
>>>
>>> ds = load(...)
>>> dd = ds.all_data()
>>> print dd.quantities.total_quantitiy("cell_mass").in_cgs()
>>>
>>> Your second message makes me wonder if there's just a slipup in how
>>> the units are returned.
>>>
>>> -Matt
>>>
>>> On Fri, May 9, 2014 at 10:37 AM, Sam Geen <samgeen at astro.ox.ac.uk> wrote:
>>>> Sorry for the spam; a second bug I've seen is that the density and
>>>> pressure
>>>> unit labels on figures appears to be broken; it seems to print a
>>>> latex-mangled code names for the units rather than the cgs name of the
>>>> units; see attached example. Temperature is fine.
>>>>
>>>>
>>>> On 09/05/14 16:28, Sam Geen wrote:
>>>>> Hi,
>>>>>
>>>>> Just to say that in the latest version of yt-3.0 (i.e. since various
>>>>> fields were renamed or re-implemented), I've found a bug in the
>>>>> implementation of "cell_mass", which is giving results that are too low
>>>>> in
>>>>> my runs; I believe the issue is that it's missing a factor of
>>>>> pf["boxlen"]**3 (which is of course only a problem if boxlen is not 1).
>>>>> The
>>>>> previous "CellMass_Msun" worked fine. If I get time I might take a look
>>>>> and
>>>>> issue a pull request, but otherwise I'm just flagging this in case
>>>>> someone
>>>>> else runs into problems; you can just manually multiply the result by
>>>>> pf["boxlen"]**3 until it's fixed.
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Sam
>>>>> _______________________________________________
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>>>>
>>>>
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