Numerics, NaNs, IEEE 754 and C99

Nick Maclaren nmm1 at cus.cam.ac.uk
Thu Jun 15 18:44:09 CEST 2006


In article <129300g5np02c8a at corp.supernews.com>,
Grant Edwards <grante at visi.com> writes:
|> 
|> > which IEEE 754 assumes that the code will test and take
|> > appropriate action (which can be anything, including aborting
|> > the program and replacing it by a NaN). See
|> > http://www.cs.berkeley.edu/~wkahan/JAVAhurt.pdf
|> 
|>   IEEE Std 754-1985, subclause 7.2 - Division by Zero
|> 
|>     "If the divisor is zero and the dividend is a finite nonzero
|>      number, then the division by zero shall be signaled. The
|>      result, when no trap occurs, shall be a correctly signed
|>      (infinity symbol)(6.3)."
|> 
|> To me it looks like the spec specifically allows for a case
|> where "no trap occurrs" and the result is Inf.

That is correct.  And it is a mandatory case.  But it does NOT say what
the software should then do with the exception.


Regards,
Nick Maclaren.



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