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Re: Center of mess [message #35982 is a reply to message #35980]

Tue, 05 August 2003 02:43

Thomas Launey
Messages: 25
Registered: September 1999

Junior Member

In article <onwudshe4a.fsf@cow.physics.wisc.edu>,
craigmnet@cow.physics.wisc.edu says...

>
> Hmm, the problem is that you are assigning pixel values with DINDGEN,
> which by default will assign 0.0 to pixel 0, 1.0 to pixel 1, and so
> on. You should add 0.5 to your pixel values, if you intend that the
> left edge of the pixel is 0.0, the right edge is 1.0, and the center
> is 0.5, etc.
>
> Y=Total(total(array,1,/double)*(dindgen(sizarr[1]) + 0.5))/totalarr
>
> and so on.
>
> Good luck,
>
> Craig
>
Actually, my solution was to add 0.5D to the returned X and Y. Still, I
am concerned that this procedure (without the "+0.5") seems to be quite
widespread in the IDL community to find centroid. Am I misunderstanding
the meaning of the returned values or is it a bug in the procedure ?
Thanks,
Thomas
--
Thomas LAUNEY
Lab. Memory and Learning, RIKEN BSI

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		Re: Center of mess By: James Kuyper on Tue, 05 August 2003 06:45
		Re: Center of mess By: Thomas Launey on Tue, 05 August 2003 02:43
		Re: Center of mess By: Craig Markwardt on Mon, 04 August 2003 22:23

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