Greetings,
I am self-learning from the python tutorial in the python docs. I am unable to wrap my head around this simple piece of code. Any kind of help is deeply appreciated.
For exactly the same reason at work here:
>>> 0.1 + 0.1 == 0.2
True
>>> 0.1 + 0.1 + 0.1 == 0.3
False
Rounding these values to one decimal digit has ne effect at all:
>>> round(0.1, 1) == 0.1
True
>>> round(0.3, 1) == 0.3
True
These decimal fractions are not exactly representable in binary floating point, and the binary approximations were already as close as it’s possible to get.
Adding the 3 copies of the closest binary approximation to 0.1 yields a sum that’s a little larger than the closest binary approximation to 0.3:
>>> import decimal
>>> decimal.Decimal(0.3)
Decimal('0.299999999999999988897769753748434595763683319091796875')
>>> decimal.Decimal(0.1 + 0.1 + 0.1)
Decimal('0.3000000000000000444089209850062616169452667236328125')
Hey Tim,
I am thankful for the knowledge shared here. This made my day. 