课程实验关于多项式相加和相减，相乘 数据结构-Add and subtract polynomials, multiply

duct.f computes a fully developed viscous laminar flow in a rectangular channel of aspect ratio b/a (=bar). solve the equation: d^2u/dx^2 + d^2u/dy^2 = -1, -a<x<a, -b<y<b method of discretisation: 3-point centered differences

多项式加法和乘法运算的设计与实现分析元素关系， 选择存储表示方法，使用单链表已有的成员函数实现多项式的相加运算，重载+、>>、<<等运算符-Polynomial addition and multiplication of elements in the design and implementation of relationship, select the storage representation, the use of single-member list