what does "-nan" mean

[torhu]

Tower Ty wrote:
> It does not mean  "null" , it does not mean "0" , it does not mean "" so just what does it signify
> 
> Not a number is cryptic . If it is not a number then just what is it ?

It's just a special bit pattern that floating point operations can 
result in when there's no sensible answer to put there.  Like when you 
divide by zero, or do other illegal operations.  If you do 
writefln(0/0.0), it will print 'nan'.