math.log versus math.log10

[Gribouillis]

If I understand well the documentation, the result of log(num, 10) is obtained by dividing log(num) by log(10), so there are rounding errors due to the division of two floating numbers at the given precision, and also perhaps to the fact that log(num) has larger magnitude that log10(num). It seems very unlikely that these rounding errors always happen in the same direction and even more unlikely that this is guaranteed by the specifications.