What does log mean?

If a n = b (a) 0, and a≠ 1), then the number n is called the logarithm with base of b, which is called n = log(a)b, where a is a subscript, where a is called "base" and b is called "true number".

Generally speaking, the function y = logax (a); 0, and a≠ 1) is called logarithmic function, that is, a function with power (real number) as independent variable, exponent as dependent variable and base constant as constant is called logarithmic function.

Where x is the independent variable, and the domain of the function is (0, +∞), that is, X; 0。 It is actually the inverse function of exponential function, which can be expressed as x=ay. Therefore, the stipulation of a in exponential function also applies to logarithmic function.

Extended data:

Logarithmic function correlation:

1, domain solution: the domain of logarithmic function y=logax is {xx}; 0}, but if you encounter the solution of the domain of logarithmic compound function, you should not only pay attention to being greater than 0, but also pay attention to the base being greater than 0 and not equal to 1.

2. Range: real number set r, obviously the logarithmic function is unbounded;

3. Fixed point: the function image of logarithmic function always passes through a fixed point (1, 0);

4. Monotonicity: a> is at 1, which is a monotone increasing function in the definition field; When 0<a< is 1, it is a monotonic decreasing function on the domain;

5. Parity: non-odd and non-even functions;

6. Periodicity: Not a periodic function.

Baidu encyclopedia-logarithm