max / min / smallest float value on Python 2.5
Christian Heimes
lists at cheimes.de
Sat Feb 6 20:55:48 EST 2010
duncan smith wrote:
> Hello,
> I'm trying to find a clean and reliable way of uncovering
> information about 'extremal' values for floats on versions of Python
> earlier than 2.6 (just 2.5 actually). I don't want to add a dependence
> on 3rd party modules just for this purpose. e.g. For the smallest
> positive float I'm using,
>
>
> import platform
> if platform.architecture()[0].startswith('64'):
> TINY = 2.2250738585072014e-308
> else:
> TINY = 1.1754943508222875e-38
>
>
> where I've extracted the values for TINY from numpy in IDLE,
>
>
> >>> float(numpy.finfo(numpy.float32).tiny)
> 1.1754943508222875e-38
> >>> float(numpy.finfo(numpy.float64).tiny)
> 2.2250738585072014e-308
You are confusing a 32 / 64bit build with 32 / 64bit floats. Python's
float type is build upon C's double precision float type on both 32 and
64 bit builds. The simple precision 32bit float type isn't used. The
DBL_MIN and DBL_MAX values are equal on all platforms that have full
IEEE 754 float point support. The radix may be different, though.
Christian
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