I think what Junhwan is asking is whether it's possible to do a profile of velocity dispersion. If I understand correctly, the problem is that this would require, for every spherical shell in a radial profile, the calculation of the standard deviation of the VelocityMagnitude field. I'm not sure if this is possible within the existing profile framework. Can anyone else comment on this?<br>
<br><div class="gmail_quote">On Wed, Feb 29, 2012 at 2:25 PM, Nathan Goldbaum <span dir="ltr"><<a href="mailto:goldbaum@ucolick.org">goldbaum@ucolick.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word"><div>Hi Junhwan,</div><div><br></div><div>Can you paste a script and a traceback that shows the error you're seeing? You should be able to pass the BulkVelocity to the derived field via set_field_parameters.</div>
<div><br></div><div>You can paste a script from the command line with the following command:</div><div><br></div><div>yt pastebin name_of_script.py</div><br><div>
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Nathan Goldbaum<br>Graduate Student<br>Astronomy & Astrophysics, UCSC<br><a href="mailto:goldbaum@ucolick.org" target="_blank">goldbaum@ucolick.org</a><br><a href="http://www.ucolick.org/%7Egoldbaum" target="_blank">http://www.ucolick.org/~goldbaum</a></div>
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<br><div><div><div class="h5"><div>On Feb 29, 2012, at 8:31 AM, Jun-Hwan Choi wrote:</div><br></div></div><blockquote type="cite"><div><div class="h5">Hi YT users,<br>
<br>
I would like to make a (spherical and/or cylindrical) profile of the velocity dispersion.<br>
In order to do so, I need to compute the mean velocity (BulkVelocity)
for a given shell (or ring), and pass this value to newly defined
velocity dispersion field, and then make a profile for the velocity
dispersion field.<br>
Is there a particular way in yt to handle this?<br>
<br>
Junhwan<br>
<br>
P.S.: A few weeks ago I posted a similar question and Matt gave me a following hint.<br>
@derived_field(name = "deltaLocalCircularVelocity")<br>
def delta_LocalCircularVelocity(fi<div>eld, data):<br>
fn, x, cv = data.get_field_parameter("local_circular_velocity")<br>
cv0 = na.interp(data[fn].ravel(), x, cv)<br>
cv0 = cv0.reshape(data[fn].shape)<br>
delta_cv = cv0 - data["LocalCircularVelocity"]<br>
return delta_cv<br>
<br>
You'll need to do something like this on the data object from which<br>
you are getting your data:<br>
<br>
sp.set_field_parameter("local_circular_velocity",<br>
(fn, prof[fn], prof["LocalCircularVelocity"]))<br>
<br>
However, it does not work for me and it is also complicate to understand and modify it.<div><div><img src=""></div></div></div><br><br clear="all">
<br>-- <br>--------------------------------------------------------------<br>Jun-Hwan Choi, Ph.D.<br>Department of Physics and Astronomy, University of Kentucky<br>Tel: <a href="tel:%28859%29%20897-6737" value="+18598976737" target="_blank">(859) 897-6737</a> Fax: <a href="tel:%28859%29%20323-2846" value="+18593232846" target="_blank">(859) 323-2846</a><br>
Email: <a href="mailto:jhchoi@pa.uky.edu" target="_blank">jhchoi@pa.uky.edu</a> URL: <a href="http://www.pa.uky.edu/%7Ejhchoi" target="_blank">http://www.pa.uky.edu/~jhchoi</a><br>
--------------------------------------------------------------<br><br><br></div></div>
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