Unexpected scientific notation

Paul McNett p at ulmcnett.com
Thu Jan 8 05:23:52 CET 2009


[Some day hopefully I'll remember to change the to: address to python-list at python.org 
instead of the original sender. I always end up sending the first reply to the 
sender, then going "oops, forgot to hit 'reply-all'", and sending another copy to the 
list.]

Ben Finney wrote:
> Paul McNett <p at ulmcnett.com> writes:
> 
>> The app bundles python 2.5.2 using py2exe.
>>
>> It displays '3E+1' instead of '30.0'.
>>
>> As I can't reproduce I'm looking for an idea brainstorm of what
>> could be causing this. What would be choosing to display such a
>> normal number in scientific notation?
> 
> As I understand it, the Python string formatting operations
> <URL:http://docs.python.org/library/stdtypes.html#string-formatting>
> use the operating system's C library to perform (some of?) the
> formatting.
> 
> The different behaviours you see might therefore be caused by
> different C libraries in the operating system.
> 
> To avoid these and related problems, I would avoid floating point
> wherever possible and use the ‘Decimal’ type for representing decimal
> numbers.

Thanks. I forgot to mention that all numbers are already instances of
decimal.Decimal, not float. As I mentioned in a prior message, they do go through a
locale.format() call to display the value.

Paul




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