Is infinity equal to infinity?

Erik Runeson <erikr@iar.se>
8 Jul 1998 01:36:08 -0400

          From comp.compilers
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From: Erik Runeson <erikr@iar.se>
Newsgroups: sci.math.num-analysis,comp.lang.c,sci.math,comp.compilers
Date: 8 Jul 1998 01:36:08 -0400
Organization: IAR Systems AB
Distribution: inet
Keywords: arithmetic, question

When comparing floating-point numbers, should infinity (Inf) be
concidered equal to infinity?


Inf == Inf ?


The IEEE 754 standard for floating-point arithmetics does not say
anything about this case, but a similar case is:


Inf - Inf = NaN


Any comparison with a NaN (Not a number) shall, according to the IEEE
754 be concidered unordered and return false. I believe that
comparing Inf with Inf should also be unordered, but this is not how it
is implemented in e.g GCC.


Any comments?


/Erik Runeson


----------------------------------------------------------------------
Erik Runeson
Email: erikr@iar.se (work, summer -98)
                d95err@csd.uu.se (home and education)
Cellphone: +46 708 723597
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