Python3,float and math, what the hell?

Mon, 14 Mar 2016 11:20:00 +0100

So it was late at night and I was hacking away at my touch-controls for my UnicornHat. I was trying to set the brightness in nine steps between 0.1 and 0.9. When all of a sudden, this happened:

>>> foo=0.1
>>> foo+=0.1
>>> print(foo)
0.2
>>> foo+=0.1
>>> print(foo)
0.30000000000000004

So according to my internal senses this looked not very precise. But according to the almighty Stackoverflow and one of my beloved coworkers who can indeed speak ASM fluently, this is in fact very precise (for a float). Since a float is merely a value, lets say, close by the one you wished it to be.

Math on Solutr.com

Python3,float and math, what the hell?