Inaccurate Logarithm in Python

Question

I work daily with Python 2.4 at my company. I used the versatile logarithm function \'log\' from the standard math library, and when I entered log(2**31, 2) it returned 31.0

Answer 1

IEEE double floating point numbers have 52 bits of precision. Since 10^15 < 2^52 < 10^16, a double has between 15 and 16 significant figures. The result 31.000000000000004 is correct to 16 figures, so it is as good as you can expect.