UNIX and Linux Applications

NAN can be generated by 0/0, but can also be generated when it tries to use a floating-point value that's actually bonkers and invalid. It's also generated by inf*0 as you suspected.

Post the actual code please. I suspect there's more to it; ordinary calculations don't just go bonkers on ordinary numbers for no reason.

Also provide your makefile so we can see exactly how you are compiling this application.

Thanks all for the replies.

Unfortunately I cannot post the code as its too huge and also for few privacy reasons.
I was able to rectify the NAN errors finally!!!.. Since the code was extremely huge, I had
some pain in locating the exact spot where the NAN was generated (It was QNAN and was propagating throughout the code).
Double datatype Addition and Multiplication were causing the errors and I typecasting the individual operands and the errors were gone!!

I have to try and do this for the rest of my code. But I am not sure why and how exactly
these errors are prevented by typecasting. Your views on this? (This code is very old,
written around 1990's for UNIX based systems)