Logarithms to the base e and to the base 10 are used extensively
in computation and in theoretical work.
Logarithms to the base 10 are called common logarithms.
Logarithms to the base e are called natural logarithms.
The following is conventional notation.
These conventions are used in most calculators.
See Example 1 - 2, pages 386 - 387.
Using the definitions of these logarithms,
is equivalent to 
.
is equivalent to 
.Applications
Sound intensity, earthquake intensity, rocket flight theory.
See Examples 3 - 7, pages 388 - 392.