Common Logarithm

The common logarithm is the logarithm to base 10. The notation logx is used by physicists, engineers, and calculator keypads to denote the common logarithm. However, mathematicians generally use the same symbol to mean the natural logarithm ln, lnx. Worse still, in Russian literature the notation lgx is used to denote a base-10 logarithm, which conflicts with the use of the symbol lg to indicate the logarithm to base 2. To avoid all ambiguity, it is best to explicitly specify log_(10)x when the logarithm to base 10 is intended. In this work, logx=log_(10)x, lnx=log_ex is used for the natural logarithm, and lgx=log_2x is used for the logarithm to the base 2.

The situation is complicated even more by the fact that number theorists (e.g., Ivić 2003) commonly use the notation log_kx to denote the nested natural logarithm [画像:ln...ln_()_(k)x].

The common logarithm is implemented in the Wolfram Language as Log [10, x] and Log10 [x].

Hardy and Wright (1979, p. 8) assert that the common logarithm has "no mathematical interest."

Common and natural logarithms can be expressed in terms of each other as

and

The common logarithm extended into the complex plane is illustrated above.

See also

Explore with Wolfram|Alpha

References

Referenced on Wolfram|Alpha

Cite this as:

Weisstein, Eric W. "Common Logarithm." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CommonLogarithm.html

Subject classifications