Re: [bug-gawk] Gawk and NaN values

[Hermann Peifer]

Nelson,

Thanks for your feedback. You wrote:
> Notice that the sign of an input NaN is always optional, and
> scripting language implementations should certainly not
> behave differently, because most are themselves implemented
> in the C language.

As stated in the GAWK manual on p.346, the leading sign is not optional 
for GAWK, but acts a signal to gawk that the value is really numeric...

I gave the example:

$ echo "1 -nan" | gawk '{print $1, $1/$2}' | gawk '{ print $1/$2 }'
awk: cmd. line:1: (FILENAME=- FNR=1) fatal: division by zero attempted

Obviously, the error can be avoided by using the --posix switch:

$ echo "1 -nan" | gawk '{print $1, $1/$2}' | gawk --posix '{print $1/$2}'
nan

However, my main issue was that gawk is able to identify -nan as a 
special Not-a-Number value, gawk does some calculations and then 
produces an output value which it can't identify as a special value (at 
least not without the --posix switch).

Hermann