Function domain is a mathematical term, which is one of the three elements of a function (domain, range and corresponding law) and the object of corresponding law. Refers to the value range of function independent variables, that is, for two non-empty sets D and M with corresponding functions, any number in set D has only one definite number corresponding to it, so set D is called function domain.
1. Constant function: the domain is a set of real numbers, and the range is constant.
2. Trigonometric function: Trigonometric functions are divided into sine function, cosine function, tangent function, cotangent function, secant function and cotangent function. The domain of sine function and cosine function is a set of real numbers, with values ranging from-1 to 1. The definition domain of tangent function is x, which is not equal to half plus k, and the range is a set of real numbers.
3. Power function: the power function must be defined in the first quadrant, and whether it is defined in other quadrants needs to be solidified according to the specific situation, depending on the situation of the definition domain.
4. Exponential function: the domain of exponential function is the range from zero to positive infinity of real number set.
5. Logarithmic function: the definition range of logarithmic function is from zero to positive infinity, and the value range is real number set.
In practical problems, the domain of function definition is not only limited by analytical formula, but also by practical meaning, such as time variables generally take non-negative numbers, and so on.