max double
Matthew Saltzman
mjs at ces.clemson.edu
Sat Dec 16 17:18:13 UTC 2006
On Sat, 16 Dec 2006, Les wrote:
> On Fri, 2006-12-15 at 19:44 -0500, Mike - EMAIL IGNORED wrote:
>> How do I find the max double on my FC4?
>> Thanks,
>> Mike.
>>
>>
> If you are discussing the size of the double precision number, you can
> look in the Math.h. The exact number will depend on the encoding and
These values are in float.h, not math.h.
> that is separate from the generic language specification. Most PC's
> rely on straight binary encoding, and so would have a range of -2e48 to
> (2e48-1) with a characteristic in binary of +32767 to -3768. The
> remaining bit sets the sign for the characteristic.
Hmm. If the values in float.h are to be believed, doubles appear to have
53-bit mantissas and exponents ranging from -1021 to 1024. Long doubles
have 64-bit mantissas and exponents ranging from -16381 to 16384. Each
representation also includes a sign bit for the mantissa.
Most PCs rely on IEEE-754 representation for floats. I think the
remaining exponent bit patterns indicate IEEE-754 states like NaN,
INFINITY, DENORM, etc. See http://en.wikipedia.org/wiki/IEEE_754 for an
intro to the gory details.
>
> Regards,
> Les H
>
>
>
--
Matthew Saltzman
Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs
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