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Re: WHERE problems (longish) [message #35909 is a reply to message #35907]

Tue, 22 July 2003 09:07

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Benjamin Panter writes:

> Yeup, thanks for that David - I'm still a bit confused though, as the
> values I give in the test program (3000.) are floats and the values in
> the look up table are also floats! I nievely thought that would avoid
> the razors and ints. Is it just by luck that where found the majority
> and lost those three?
>
> After reading your pages I've come up with a solution though... if I
> replace the where lines with
>
> print, where(abs(3000. - reform(dust_lookup[*,0])) lt 0.1)
>
> I come out with the right answer.

And that would be the right approach. With floats
you can't (generally) ask if one float *equals*
another. You can ask if one float is within some
very tiny delta of another. That's what you ended
up doing here, and it works spectacularly. :-)

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: WHERE problems (longish) By: Paul Van Delst[1] on Tue, 22 July 2003 09:45
		Re: WHERE problems (longish) By: David Fanning on Tue, 22 July 2003 09:07
		Re: WHERE problems (longish) By: Benjamin Panter on Tue, 22 July 2003 08:59
		Re: WHERE problems (longish) By: Justin[2] on Tue, 22 July 2003 08:49
		Re: WHERE problems (longish) By: David Fanning on Tue, 22 July 2003 08:47

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