一个控制台中缀表达值求值程序，相当于一个科学计算器。只支持四则运算，不能纠错。数据结构必备。-A console infix expression value of the evaluation procedure, the equivalent of a scientific calculator. Only supports four operations, not error correction. Data structure is essential.

从随机的数据中找出其规律性，给出其近似表达式的问题，在生产实践和科学实验中大量存在，通常利用数据的最小二乘法求得拟合曲线。-From random data to find its regularity, give its approximate expression problems in the production practice and scientific experiments abound, often use the data obtained by least squares