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Code Directories:
16 June 2006
A couple of new IDL tidbits that should help me on my way. First of all, I found a program
called newsimp on some website. This program will do a numerical integration, and hopefully
will be a decent approximation. Also, I learned how to define my own global variables:
defsysv, '!var_name', var_value
15 June 2006
Just a quick note here. IDL doesn't appear to have an inverse hyperbolic tangent
function, so I'm using the definition from Wolfram's MathWorld, which is as follows:
tanh-1(z)=1/2*[ln(1+z) - ln(1-z)]
But, since I'm only using this for |z| < 1, I can use the simplified version:
tanh-1(z)=1/2*ln[(1+z)/(1-z)]
13 June 2006
A couple of things regarding the calculation of &tau. First of all, for the contours,
I've found that I have to reverse the x-axis to get the contours to appear in the
correct orientation with respect to the velocities in the color contour plots.
This, I believe, is because the sign conventions for the two are different. For
line-of-sight velocity, negative velocities mean that material is coming towards the
observer, so having x be negative in those areas makes sense. But, for optical
depth (&tau), one basically has to integrate from the x-position of the material out
to infinity towards the observer, so the sign has to be opposite that of vlos.
I also really just don't have much faith in my calculation of &tau at this point. In
addition (and this is mentioned in one of the papers), calculating &tau where p (or, for
me, y) is less than or equal to 1 is tricky, but the paper doesn't specify any further.
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