[issue18613] wrong float plus/minus op result

2013-08-01 Thread Laurent Fournier 

Laurent Fournier added the comment:

also with addition !

print (.05+.01)
0.065

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title: wrong float minus op result - wrong float plus/minus op result

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[issue18613] wrong float plus/minus op result

2013-08-01 Thread Brett Cannon 

Brett Cannon added the comment:

This is actually expected because that is just how floating point works in 
programming (see http://en.wikipedia.org/wiki/Floating_point for all the gnarly 
details).

If you want exact decimal arithmetic, use the decimal module (which got 
significantly faster in Python 3.3)::

 import decimal
 decimal.Decimal('.3') - decimal.Decimal('.1')
Decimal('0.2')
 decimal.Decimal('.05') + decimal.Decimal('.01')
Decimal('0.06')

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nosy: +brett.cannon
resolution:  - invalid
status: open - closed

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