polyfit函数是matlab中用于进行曲线拟合的一个函数。其数学基础是最小二乘法曲线拟合原理。曲线拟合：已知离散点上的数据集，即已知在点集上的函数值，构造一个解析函数（其图形为一曲线）使在原离散点上尽可能接近给定的值。(The polyfit function is a function used in curve fitting in matlab. Its mathematical basis is the principle of least-squares curve fitting. Curve fitting: Known data sets at discrete points, known as function values on the point set, construct an analytical function (the graph is a curve) so that the original discrete point is as close as possible to a given value.)