常用的一些函数的拟合算法，包括多项式、指数、对数和幂函数等；可以设置截距、权重，不依赖第三方库，跨平台运行。(Commonly used function fitting algorithms, including polynomials, exponents, logarithms and power functions; intercepts can be set, weight, independent of third-party libraries, cross-platform op