[yt-users] Projection Question

David Collins dcollins4096 at gmail.com
Fri Apr 12 15:32:02 PDT 2013


Ah, right on.  Thanks!

d.


On Fri, Apr 12, 2013 at 4:17 PM, Matthew Turk <matthewturk at gmail.com> wrote:

> On Fri, Apr 12, 2013 at 6:13 PM, david collins <dcollins4096 at gmail.com>
> wrote:
> > Hi, all--
> >
> > I have a dumb projection question.
> >
> > Why is it that when I do a projection, the minimum pdx is smaller than
> the
> > minimum cell width in my simulation?
> >
> >>>> pf.h.get_smallest_dx()
> > 0.0001220703125
> >>>> 1./pf.h.get_smallest_dx()
> > 8192.0
> >
> > Additionally, the sum of the areas is not what I expect.  I expect
> >
> >>>> proj=pf.h.proj(0,'Density')
> >>>> (proj['pdx']*proj['pdy']).sum()
> > 0.25
> >
> >
> > I get 0.25, instead of 1 (consistent with the above, if all the widths
> are
> > down by a factor of 2.)
> >
> > I assumed that proj['pdx'] is the width of the zone of the projection,
> which
> > I naievely expect to be the smallest cell width along any line of sight.
> >
> > Could one of you good people fill in what I'm misunderstanding?
>
> Sure!  pdx is halfwidth, and the px values are cell centers.  I think
> this is somewhere in the method paper, but there's no clear place to
> stick it in the documentation.
>
> -Matt
>
> >
> > Thanks a ton!
> > d.
> >
> > _______________________________________________
> > yt-users mailing list
> > yt-users at lists.spacepope.org
> > http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
> >
> _______________________________________________
> yt-users mailing list
> yt-users at lists.spacepope.org
> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.spacepope.org/pipermail/yt-users-spacepope.org/attachments/20130412/7882cf1f/attachment.htm>


More information about the yt-users mailing list