[Ironpython-users] IronPython float_info values (was: IronPython always in 32-bit mode on 64bit machine even when running ipy64.exe)

Curt Hagenlocher curt at hagenlocher.org
Wed May 8 17:33:57 CEST 2013


You can get precise values of these without depending on the compiler's
ability to convert text to floating point values by saying

sys.float_info.min =
System.BitConverter.Int64BitsToDouble(0x0010000000000000)  # i.e. 2^-1023
sys.float_info.epsilon =
System.BitConverter.Int64BitsToDouble(0x3cb0000000000000) # i.e. 2^-53



On Wed, May 8, 2013 at 8:10 AM, Jeff Hardy <jdhardy at gmail.com> wrote:

> On Wed, May 8, 2013 at 4:07 AM, Markus Schaber <m.schaber at codesys.com>wrote:
>
>>  Hi,****
>>
>> ** **
>>
>> http://www.johndcook.com/blog/2010/06/08/c-math-gotchas/ explains the
>> problem: The double.MinValue and double.Epsilon in C# have different
>> meanings thant DBL_MIN and DBL_EPSILON in C.****
>>
>> ** **
>>
>> I'm looking for a way how to get the wanted values… J
>>
>
> So am I! .NET does not provide them as constants as far as I can tell. I'm
> pretty sure .NET requires the use of IEEE-854 floats so they could probably
> just be hardcoded to match the C constants but ... ick. Maybe there's a way
> to calculate the C versions from what .NET provides?
>
> The relevant issue is https://ironpython.codeplex.com/workitem/27840.
>
> - Jeff
>
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