trapping NaN

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2 total messages Started by J. G. Gregory Fri, 20 Nov 1992 22:10

#1871

Author: J. G. Gregory
Date: Fri, 20 Nov 1992 22:10

6 lines
555 bytes

I would like to trap NaN -- the "not a number" condition that floating point  
values can take.  I can't find any clue on how to do this, except some cryptic  
stuff in the man pages under "math".  Is there some signal I can handle?

Thanks in advance.
--J Gregory

Re: trapping NaN

#1876

Author: Ralph Zazula
Date: Sat, 21 Nov 1992 18:13

31 lines
1244 bytes

In article <1992Nov20.221038.1170@proforma.com>  writes:
> I would like to trap NaN -- the "not a number" condition that floating point  
> values can take.  I can't find any clue on how to do this, except some  
cryptic  
> stuff in the man pages under "math".  Is there some signal I can handle?
> 
> Thanks in advance.
> --J Gregory

Hi -

It turns out that (NaN != NaN) is true.  So, in some code I did before, I used:

if(x == x) {	/* x is NOT NaN */
< use x>
}
else {
<whatever for the NaN case>
}

Here's the excerpt from the manual page:

"If x != x then x is NaN; every other predicate (x > y, x = y, x < y,...) is  
FALSE if NaN is involved."

Ralph
---
Ralph Zazula
Pinnacle Research, Inc.
zazula@pri.com (NeXT Mail)
(602)529-1135

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