Logarithmic symbol log is derived from Latin logarithm and was first used by Italian mathematician cavalieri. At the beginning of the 20th century, the modern representation of logarithm was formed. For the convenience of use, people gradually recorded the common logarithm with the base of 10 and the natural logarithm with the base of irrational number e as lgN and lnN respectively.

In mathematics, logarithm is the inverse operation of power, just as division is the reciprocal of multiplication, and vice versa, that is to say, the logarithm of a number is the exponent that must produce another definite number (radix). In a simple case, the logarithmic counting factor in the multiplier. More generally, the power operation allows any positive real number to be raised to any power, and always produces positive results, so the logarithm of any two positive real numbers b and x whose b is not equal to 1 can be calculated.