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Re: divide by zero problems
- Subject: Re: divide by zero problems
- From: korpela(at)albert.ssl.berkeley.edu (Eric J. Korpela)
- Date: 15 May 1999 02:21:58 GMT
- Newsgroups: comp.lang.idl-pvwave
- Organization: Cal Berkeley-- Space Sciences Lab
- References: <3737C79C.372FA82E@aims.gov.au> <7hfhke$gn7$1@clam.niwa.cri.nz> <7hhrbb$k3a$1@hammer.msfc.nasa.gov> <bowman-1405991756240001@tl6-218-141.tca.net>
- Xref: news.doit.wisc.edu comp.lang.idl-pvwave:14761
In article <bowman-1405991756240001@tl6-218-141.tca.net>,
Kenneth P. Bowman <bowman@null.tamu.edu> wrote:
>> IDL> PRINT, !VALUES.F_NAN EQ !VALUES.F_NAN
>> 1
>> % Program caused arithmetic error: Floating illegal operand
>
>I thought that by definition NaNs are not a number and hence not equal to
>*anything* else. Thus the FINITE function.
That's the point. In IEEE math there is no need for a FINITE function.
X eq X is enough to test for NaN. X EQ !Values.F_NAN should always return
0. Even if X is NaN. Period. Excamation point!
If RSI thinks it's not important that IDL be IEEE compliant, they're wrong.
I may consider that bit of non-portability/non-compliance a good reason not
to code for IDL under ANY platform.
Eric
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