In mathematics, the big O symbol and the small O symbol are mathematical symbols used to describe the asymptotic behavior of functions.

Big O notation is a mathematical symbol used to describe the asymptotic behavior of a function. More precisely, it uses another (usually simpler) function to describe the asymptotic upper bound of the function order.

The small O symbol indicates that one function is gradually smaller than another function and is not equal to.

The big O symbol is very useful in analyzing the efficiency of the algorithm. For example, the time (or number of steps) required to solve a problem of scale n can be obtained as follows: t (n) = 4n 2-2n+2.

When n increases, n 2; Item will start to dominate, while other items can be ignored-for example, when n = 500, 4n^2；; This term is 1000 times larger than 2n term, so in most cases, the influence of omitting the latter on the expression value will be negligible.

The basic methods for finding the limit are:

1. When the numerator and denominator in the fraction are divided by the highest degree, infinity is calculated as infinitesimal, and infinitesimal is directly substituted into 0.

2. Minus infinite roots, molecules are physical and chemical.

3. Apply the Lobida rule, but the application condition of the Lobida rule is that it is transformed from infinity to infinity or infinitesimal to infinitesimal, and the numerator denominator must also be a continuous derivative function.