[rrd-developers] Re: Representation of NAN and INF

[Tobias Oetiker]

Jul 25 Chris Carton wrote:

 |
 | http://allserv.rug.ac.be/unix/software/workshop/manuals/c/user_guide/data.represent.html
 |
 | I scanned that page quickly and believe that the answer you're looking for is
 | there.
 |
 | Chris
 |
 |
 | >> I note in the C source that these two pseudo-numbers have representation
 | >> defined in terms of the particular float scheme used with the C compiler:
 | >>
 | >> #define DNAN    ((double)(0.0/0.0))
 | >> #define DINF    ((double)(1.0/0.0))
 | >>
 | >> Apparently, these two representations come out different. However, in the
 | >> math I studied, "anything" divided by 0 is still ... like Undefined. And so
 | >> 0/0 is the same as 1/0 and both are illegal.

you also might want to take a look at the configure.in file it
contains a neat little test program to figure out how well your
compiler handles the NAN / INF problem ... its quite a pain to
support all the different systems

tobi
 |
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