Hi Max, Someone can correct me if I'm wrong, but I'm fairly sure that if you create a derived field, in this case XRayEmissivity, when you create a BinnedProfile it should be calculating the XRayEmissivity for each point before binning it up. Therefore I think what you would want to do is something like prof = BinnedProfile1D(data_source, n_bins, 'Radius', r_min, r_max) prof.add_fields(['XRayEmissivity], weight=None, accumulation=True) The accumulation=True keyword tells it to sum it up as it goes out in radius. This makes it a cumulative distribution. There are some more docs on the BP1D here: http://yt-project.org/doc/reference/api/generated/yt.data_objects.profiles.B... including ways to write it out. You may also want to check out the PlotCollection.add_profile_sphere: http://yt-project.org/doc/reference/api/generated/yt.visualization.plot_coll... which provides a wrapper around the BinnedProfile1D object. Let us know if that works. Best, Sam On Mon, Apr 23, 2012 at 9:17 AM, Massimo Gaspari <gaspmax@hotmail.com>wrote:

Hi guys,

I am trying to calculate the (X-ray) luminosity within a sphere of radius r: Lx = sum emissivity *dvol (within r)

Suppose I have defined a new derived field XRayEmissivity, dependent on data['Density'] and data['Temperature'].

How would you carry out that?

I am trying to use BinnedProfile1D. However, it seems that the derived fields are computed only *after* binning, e.g. XRayEmissivity = <Density>**2 * <Temperature>^0.5

I don't want to use the averaged quantities (in each shell). I would like to compute the emissivity point by point, for each leaf block (very important for the luminosity).

Is it possible?

Thanks, as always!

Max

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