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Re: How do I prevent underflow errors? [message #14362 is a reply to message #14351]

Wed, 17 February 1999 00:00

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

Phillip & Suzanne David <pdavid@earthling.net> writes:
>
> I have a large array of data that I'd like to plot with the contour routine.
> However, the dynamic range of the data is very large, with values as large as
> 1e36 and as small as 1e-40. I noticed that contour accepts float data, not
> double data. This data is outside the range of float data, so it needs to be
> scaled for the contour routine. I don't really care to differentiate the
> 1e-40 from 0, but would like to be able to handle values up to the 1e36. I
> was going to scale the data by the largest value (i.e.,
> PlotData=Float(Data/Max(Abs(Data)))). This puts the data in the range of -1.0
> to 1.0. This should be fine for Contour, but I get an underflow error when
> converting from double data to float data. I understand that the data will
> come out with a 0 instead of 1e-76, and don't really care. How do I get IDL
> to ignore the underflow and just convert the value?
>
> Phillip
>

Greetings,

Try the following with check_math(), which is documented in IDL.

dummy = check_math(1, 1)
.... commands with math errors are placed here ...
dummy = check_math(0, 0)

Most of your messages will go away (except for maybe the last one).

Craig

--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@astrog.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: How do I prevent underflow errors? By: Ethan Alpert on Fri, 19 February 1999 00:00
		Re: How do I prevent underflow errors? By: meron on Thu, 18 February 1999 00:00
		Re: How do I prevent underflow errors? By: thompson on Thu, 18 February 1999 00:00
		Re: How do I prevent underflow errors? By: Phillip & Suzanne on Wed, 17 February 1999 00:00
		Re: How do I prevent underflow errors? By: meron on Wed, 17 February 1999 00:00
		Re: How do I prevent underflow errors? By: Ethan Alpert on Wed, 17 February 1999 00:00
		Re: How do I prevent underflow errors? By: Michael Viskum on Wed, 17 February 1999 00:00
		Re: How do I prevent underflow errors? By: Craig Markwardt on Wed, 17 February 1999 00:00
		Re: How do I prevent underflow errors? By: davidf on Tue, 16 February 1999 00:00

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