floats default to NaN... why?

[Jerome BENOIT]

On 14/04/12 09:45, F i L wrote:
> Jonathan M Davis wrote:
>> No. You always have a bug if you don't initialize a variable to the value that
>> it's supposed to be. It doesn't matter whether it's 0, NaN, 527.1209823, or
>> whatever. All having a default value that you're more likely to use means is
>> that you're less likely to have to explicitly initialize the variable. It has
>> to be initialized to the correct value regardless.
>
> Yes, I'm in favor of default values. That's not my argument here. I'm saying it makes more sense to have the default values be _usable_ (for convenience) rather than designed to catch (**cause**) bugs.
>

Why would a compiler set `real' to 0.0 rather then 1.0, Pi, .... ?
The more convenient default set certainly depends on the underlying mathematics,
and a compiler  cannot (yet) understand the encoded mathematics.
NaN is certainly the certainly the very choice as whatever the involved mathematics,
they will blow up sooner or later. And, from a practical point of view, blowing up
is easy to trace.

>