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Re: Maximum radius of SEARCH2D/SEARCH3D [message #34729 is a reply to message #34728]

Mon, 14 April 2003 13:56

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Alexander Gro� (AlexanderGross_NOSPAM@gmx.de) writes:

> thank you very much. It's working good. For the distance caluculation I used
> a for loop. I did not implement the square root function for distance
> calculation since this costs CPU time. I raised the allowed maximum radius
> to the power of two and compare it to the computed distance each time.
>
> Only for my understanding: Is is possible to do this without the "evil" for
> loop? Is there another way to tell IDL that the operation has to be done for
> each element of the subscripts array?

For the 2D case, I was envisioning something like this:

indices = Search2d(array, x, y)
s = Size(array, /Dimensions)
cols = indices MOD s[0]
rows = indices / s[0]
radius = Sqrt( (cols - x)^2 + (rows - y)^2)
goodPixels = Where(radius LT myCircleRadius)
cols = cols[goodPixels]
rows = rows[goodPixels]

> Thank you very much for sharing your deep insight of IDL. :-)

I think you have me confused with JD. :-)

Cheers,

David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

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[Message index]

		Re: Maximum radius of SEARCH2D/SEARCH3D By: David Fanning on Mon, 14 April 2003 19:03
		Re: Maximum radius of SEARCH2D/SEARCH3D By: Alexander Gro� on Mon, 14 April 2003 14:28
		Re: Maximum radius of SEARCH2D/SEARCH3D By: David Fanning on Mon, 14 April 2003 13:56
		Re: Maximum radius of SEARCH2D/SEARCH3D By: Alexander Gro� on Mon, 14 April 2003 13:41
		Re: Maximum radius of SEARCH2D/SEARCH3D By: David Fanning on Mon, 14 April 2003 06:16
		Re: Maximum radius of SEARCH2D/SEARCH3D By: David Fanning on Mon, 14 April 2003 06:13
		Re: Maximum radius of SEARCH2D/SEARCH3D By: Alexander Gro� on Wed, 16 April 2003 14:08

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