Floating point precision while using Python's max()

Question

Why so?

>>> max(2, 2.01)
2.0099999999999998

Answer 1

because:

>>> 2.01
2.0099999999999998

it's the way floating point numbers are stored

Answer 2

Floating point numbers do not encode exact values, but approximations. The result is essentially the next nearest floating point number to the real number you entered.

http://docs.python.org/tutorial/floatingpoint.html

Answer 3

Floating point roundoff. Its trying to say 2.01 but can't express it exactly as a floating point number so its doing the best it can.

Answer 4

The number 2.01 represented in binary is:

b10.00000010100011111100001010001111110000101000111111000010100011111100...

The computer uses only a finite number of digits to store floating-point values, but the binary representation of 2.01 requires infinitely many digits; as a result, it is rounded to the closest representable value:

b10.000000101000111111000010100011111100001010001111110

Expressed in decimal, this number is exactly:

2.0099999999999997868371792719699442386627197265625

When you print it out, it is rounded a second time to seventeen decimal digits, giving:

2.0099999999999998