c++版数值分析各种算法

#include < iostream.h > #include < math.h > void main() { int n1,n; cout << "请输入节点个数："<<endl; cin >> n1; n = n1-1 ; double * x = new double [n+1]; double * y = new double [n+1]; double xx = 0; double yy = 0; cout << "请输入各个节点："<<endl; for(int i=0; i<=n; i++) cin >> x[i] >> y[i]; cout << "请输入要求的节点："<<endl; cin >> xx; double * h = new double [n]; for( i=0; i<=n-1; i++) h[i] = x[i+1]-x[i]; double * a = new double [n+1]; double * b = new double [n+1]; double * m = new double [n+2]; int choice; cout << "\n1.第一种边界条件(手动输入m[0],m[n]);"<<endl; cout << "2.第二种边界条件(m[0]=0,m[n]=0);"<<endl; cout << "\n请选择边界条件：" <<endl; cin >> choice; switch (choice) { case 1: cout << "m[0]=" ; cin >> m[0]; cout << "m[n]=" ; cin >> m[n]; a[0] = 0; b[0] = 2*m[0]; a[n] = 1; b[n] = 2*m[n]; break; case 2: a[0] = 1; b[0] = 3*(y[1]-y[0])/h[0]; a[n] = 0; b[n] = 3*(y[n]-y[n-1])/h[n-1]; break; default: cout << "输入错误！"<<endl; } for ( i = 1; i<=n-1; i++) { a[i] = h[i-1]/(h[i-1]+h[i]) ; b[i] = 3*((1-a[i])*(y[i]-y[i-1])/h[i-1] + a[i]*(y[i+1]-y[i])/h[i]) ; } double * a1 = new double [n+1]; double * b1 = new double [n+1]; for ( i=0; i<=n; i++) { if(i==0) { a1[i] = -a[i]/2 ; b1[i] = b[i]/2 ; } a1[i] = -a[i]/(2 + (1-a[i])*a1[i-1]) ; b1[i] = (b[i]-(1-a[i])*b1[i-1])/(2 + (1-a[i])*a1[i-1]) ; } m[n+1] = 0 ; for ( i=n; i>=0; i--) m[i] = a1[i]*m[i+1]+b1[i] ; int key = 0 ; for ( i=0; i<=n-1; i++) { if(xx>=x[i] && xx<=x[i+1]) key = i ; } if(key>=n) { cout << "error!" <<endl; return; } yy = (1+2*(xx-x[key])/(x[key+1]-x[key]))*pow((xx-x[key+1])/(x[key]-x[key+1]),2)*y[key] ; yy += (1+2*(xx-x[key+1])/(x[key]-x[key+1]))*pow((xx-x[key])/(x[key+1]-x[key]),2)*y[key+1] ; yy += (xx-x[key]) *pow((xx-x[key+1])/(x[key]-x[key+1]),2)*m[key] ; yy += (xx-x[key+1])*pow((xx-x[key])/(x[key+1]-x[key]),2)*m[key+1] ; cout << yy <<endl; }