Problem with Decimal Floating Point

[knan]

We know that 0.1 + 0.1 + 0.1 - 0.3 = 0.0
But in python 0.1 + 0.1 + 0.1 - 0.3 = 5.5511151231257827e-017

Is there any way I can get 0.0...??

[SgtMe]

Well a simple fix would be to multiply everything by 10. Ie:

import os
print float(1+1+1-3)/10
os.system("pause")

[pyTony]

To be at sure side add in beginning of your numeric Python 2 code:

from __future__ import division

This makes 1/4 produce 0.25, not 0 (integer division). For integer division use // operator.

[Gribouillis]

Start with this documentation page http://docs.python.org/tutorial/floatingpoint.html .

A problem is that python's 0.1 is not the mathematical 0.1 because 0.1 can not be represented exactly as a machine binary number.

[woooee]

The limits of floating point numbers
http://www.lahey.com/float.htm
http://docs.python.org/tutorial/floatingpoint.html
Use decimal for more precision.

from decimal import Decimal as dec

# 0.1 + 0.1 + 0.1 - 0.3 = 0.0
x = dec("0.1")
y = dec("0.3")
print x + x + x - y

[knan]

Thank you very much everyone... Now i understand the reason behind it... Thank you!