由于本学期有一门计算方法的课需要C语言编程，在这里记录一下。
由于这是第一章且后面的课大约也有相似的属性，比如对n个点的使用和函数的调用，这里就进行一个小封装，方便以后吃老本。
欢迎需要参考的同学复制粘贴，互相交流.
//POINTS.h #pragma once #include<vector> using namespace std; #ifndef _POINTS_ #define _POINTS_ class POINTS { public: typedef struct MYPOINT { double x; double y; }mypoint; int len; int size; virtual void run(double val); virtual void loaddata(double* vallist); }; #endif // !_POINTS_
//POINTS.cpp #include "POINTS.h" #include<iostream> using namespace std; void POINTS::run(double val) { cout << "计算函数" << endl; } void POINTS::loaddata(double* vallist) { cout << "数据处理函数" << endl; }
//LAGRANGE.h #pragma once #include "POINTS.h" #ifndef _LAGRANGE_ #define _LAGRANGE_ class LAGRANGE : public POINTS { public: LAGRANGE(int n); vector<mypoint> datalist; virtual void run(double val); virtual void loaddata(double* vallist); }; #endif // !LAGRANGE
//LAGRANGE.cpp #include "LAGRANGE.h" #include<iostream> using namespace std; LAGRANGE::LAGRANGE(int n) :datalist(n) { this->size = n; this->len = 0; } void LAGRANGE::run(double val) { double sum = 0.0; vector<double> templist; for (size_t i = 0; i < this->size; i++) { double tempval = 1.0; for (size_t j = 0; j < this->size; j++) { if (j != i) tempval *= ((val - this->datalist.at(j).x) / (this->datalist.at(i).x - this->datalist.at(j).x)); else continue; } templist.push_back(tempval); } for (size_t i = 0; i < this->size; i++) { sum += this->datalist.at(i).y * templist.at(i); } cout << "拉格朗日" << this->size << "项插值计算为：" << sum << endl; } void LAGRANGE::loaddata(double* vallist) { cout << "正在处理数据..." << endl; for (size_t i = 0; i < this->size * 2; i++) { if (((i + 1) % 2) == 0) { this->datalist.at(this->len).y = vallist[i]; this->len++; } else { this->datalist.at(this->len).x = vallist[i]; } } }
//main.cpp #include<iostream> #include"POINTS.h" #include"LAGRANGE.h" using namespace std; int main() { cout << "例1" << endl; //实例化工具类 LAGRANGE lgr(2); //构建运算参数表 double val[4] = { 100.0,10.0,121.0,11.0 }; //调用处理数据函数 lgr.loaddata(val); //传入目标x运算,例1 lgr.run(115); //传入目标x运算,例2 cout << "例2" << endl; LAGRANGE lgr1(3); double val1[6] = { 100.0,10.0,121.0,11.0,144.0,12.0 }; lgr1.loaddata(val1); lgr1.run(115); //课上的题目求ln3.16 cout << "求ln3.16" << endl; LAGRANGE lgr2(2); double val2[4] = { 3.1,1.1314,3.2,1.1632 }; lgr2.loaddata(val2); lgr2.run(3.16); system("pause"); return 0; }
