[yt-users] A basic question how yt treat the intersect cell.

[Jun-Hwan Choi]

Thank you Matt.
Now I understand what is going on inside of profile and objects.

Junhwan
On 05/07/12 14:53, Matthew Turk wrote:
> On Mon, May 7, 2012 at 2:50 PM, Jun-Hwan Choi<choi.junhwan at gmail.com>  wrote:
>> Thanks Matt,
>>
>> To make clear your statement, the cells are never interpolated when we make
>> profile and objects.
>> When yt compute the cell's location, it compute the center of the cell.
>> Therefore, if I make r vs M(r) profile, the cell's mass goes to the radius
>> bin with which the cell's center corresponds, regardless of the size of
>> cell.
>> Is it correct?
> Yup.  If you want to have radial bins that are smaller than your cell
> size, you could use the covering_grid functionality and manually
> calculate your profiles.
>
> -Matt
>
>> Thank you,
>> Junhwan
>>
>>
>> On 05/07/12 13:10, Matthew Turk wrote:
>>> Hi Junhwan,
>>>
>>> On Mon, May 7, 2012 at 12:02 PM, Jun-Hwan Choi<jhchoi at pa.uky.edu>    wrote:
>>>> Hi all,
>>>>
>>>> I have one conceptual question.
>>>> When you make a profile, what happen one grid cell (finest cell) is
>>>> bigger
>>>> than one bin?
>>> Typically profiles do not get applied to spatial dimensions.  Profiles
>>> bin cells based explicitly on the value of the profiled field; cells
>>> contain one definitive field value for each field, not multiple, so it
>>> will only get placed into a single bin.
>>>
>>>> Does yt interpolate the physical value (mass, density, velocity ...) and
>>>> assign the appropriate value to the bins which the cell intersects?
>>>> The very similar question is what happen one grid cell (finest)
>>>> intersects
>>>> with object boundary.
>>>> For example, I define sphere and try to measure total mass of sphere.
>>>> Does yt interpolate the mass of cell that intersects with the object's
>>>> boundary and compute the partial mass of cell to assign to total mass of
>>>> the
>>>> sphere?
>>> No, cells are not interpolated.  Data objects apply a strict cutoff
>>> based on cell-centers.  So if you have a sphere, and your sphere
>>> intersects a cell center, that cell will be included in analysis of
>>> that sphere.  If you want to apply additional cutoffs based on spatial
>>> characteristics you can, but you will have to explicitly apply them.
>>>
>>> -Matt
>>>
>>>> If yt interpolate the cell, does yt use a particular weight?
>>>> This issue may be important, when one need to compute fine physical
>>>> quantities.
>>>>
>>>> Thanks in advance,
>>>> Junhwan
>>>>
>>>> --
>>>> --------------------------------------------------------------
>>>> Jun-Hwan Choi, Ph.D.
>>>> Department of Physics and Astronomy, University of Kentucky
>>>> Tel: (859) 897-6737        Fax: (859) 323-2846
>>>> Email: jhchoi at pa.uky.edu   URL: http://www.pa.uky.edu/~jhchoi
>>>> --------------------------------------------------------------
>>>>
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>>
>>
>> --
>> --------------------------------------------------------------
>> Jun-Hwan Choi, Ph.D.
>> Department of Physics and Astronomy, University of Kentucky
>> Tel: (859) 897-6737        Fax: (859) 323-2846
>> Email: jhchoi at pa.uky.edu   URL: http://www.pa.uky.edu/~jhchoi
>> --------------------------------------------------------------
>>
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-- 
--------------------------------------------------------------
Jun-Hwan Choi, Ph.D.
Department of Physics and Astronomy, University of Kentucky
Tel: (859) 897-6737        Fax: (859) 323-2846
Email: jhchoi at pa.uky.edu   URL: http://www.pa.uky.edu/~jhchoi
--------------------------------------------------------------