hermite.cpp

常用的数值分析算法

#include<iostream.h>
#define N 10

double Hermite(double x,double xj[N],double yj[N],double mj[N])
{   int   k,j;   
    double   res,ldao,a,lix,b;   
    res=0.0;       
  for(j=0;j<N;j++)   
      {   
         ldao=0.0;    
		 lix=1.0;   
    for(k=0;k<N;k++)   
       {   
              if(k!=j)   
			  {        
				       lix=lix*(x-xj[k])/(xj[j]-xj[k]);  
                       ldao=ldao+1/(xj[j]-xj[k]); 
              } 
			  
                 
	   } 
	             
	             a=(1-2*(x-xj[j])*ldao)*(lix*lix);
		         b=(x-xj[j])*(lix*lix);
                 res=res+(yj[j]*a+mj[j]*b);   
      }   
                 

                return(res); 
}

int main()
{  double ini,res;
   double x[N]={0.10,0.20,0.30,0.40,0.50,0.60,0.70,0.80,0.90,1.00};
   double y[N]={0.904837,0.818731,0.740818,0.670320,0.606531,0.548812,0.496585,0.449329,0.406570,0.367879};
   double m[N]={-0.904837,-0.818731,-0.740818,-0.670320,-0.606531,-0.548812,-0.496585,-0.449329,-0.406570,-0.367879};
   cout<<"please input a x:\n";
   cin>>ini;
   res=Hermite(ini,x,y,m);
   cout<<"the result is:"<<res<<endl;
   return 0;
}