| Re: GAUSS2DFIT - TILT ? [message #22923 is a reply to message #22787] |
Mon, 11 December 2000 10:42  |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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Hi Thomas--
I get problems with your program as well, as shown here.
constant scale width_x width_y center_x center_y tilt
Should: 5.000 100.000 16.000 6.400 64.000 76.800 1.000
Is: 4.841 100.218 7.378 10.076 63.884 76.800 0.000
This exact subject came up a few months ago by Ken Bowman. I
suggested he try MPFIT2DPEAK, available from my IDL library. So far I
have found this routine to be a little more robust in finding peaks
and establishing rotations.
In your example I obtained the "right" answer with MPFIT2DPEAK:
IDL> yfit = mpfit2dpeak(z, b,xvec,yvec,/tilt)
Should: 5.000 100.000 16.000 6.400 64.000 76.800 1.000
Is: 4.999 100.004 6.386 16.007 63.995 76.814 2.571
Note that the fitted X and Y axes are flipped from your initial
definition, hence the fitted value of 2.571 = 1.000 + !dpi/2. Of
course you can easily put the semi-major axis under the X column with
a simple transformation.
http://cow.physics.wisc.edu/~craigm/idl/idl.html
Craig
IDL> print, !version
{ x86 linux unix 5.2.1 Jun 4 1999}
"Zeschke" <zeschke@bessy.de> writes:
> Why does the following example not work correctly ?
> This program use the "GAUSS2DFIT.PRO" - Routine. The "Tilt"-Parameter-Fit
> does not work.
> What can I do ?
>
>
> Thanks for any help
> Thomas
--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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