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From: Grant Edwards <invalid@invalid.invalid>
Newsgroups: comp.lang.python
Subject: Re: Python Front-end to GCC
Date: Fri, 25 Oct 2013 19:06:27 +0000 (UTC)
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On 2013-10-25, Mark Janssen <dreamingforward@gmail.com> wrote:
>>>>> OTOH why in particular would you want to initialise them with zeros? I
>>>>> often initialise arrays to nan which is useful for debugging.
>>>
>>> Is this some kind of joke?  What has this list become?
>>
>> It's a useful debugging technique to initialize memory to distinctive
>> values that should never occur in real data.
>
> If you're doing this, you're doing something wrong.

Pardon me if I don't take your word for it.

> Please give me the hex value for NaN so I can initialize with my
> array.

Seriously?  You haven't discovered google and wikepedia yet?

   http://www.google.com/
   http://en.wikipedia.org/   

Assuming you're using IEEE-754, all 1's is a quiet NaN:

   http://en.wikipedia.org/wiki/IEEE_floating_point
   http://en.wikipedia.org/wiki/NaN

If you want a signaling NaN you've got to change one of the bits (see
the above links).

IIRC, the Pascal language required that using unintialized variables
caused an error. intializing FP values to a signalling NaN is a very
convenient way to do that.

-- 
Grant Edwards               grant.b.edwards        Yow! I'm also against
                                  at               BODY-SURFING!!
                              gmail.com