四阶龙格-库塔法.cpp

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#include<iostream.h>

double f(double x,double y);
 
void main()
{
 double x0,y0,h,x1,y1,K1,K2,K3,K4;
 int n;
 x0=0;
 y0=1;
 h=0.2;
 for(n=1;n<=5;n++)
 {
   x1=x0+h;
   K1=f(x0,y0);
   K2=f(x0+0.5*h,y0+0.5*K1*h);
   K3=f(x0+0.5*h,y0+0.5*K2*h);
   K4=f(x1,y0+K3*h);
   y1=(K1+2*K2+2*K3+K4)*h/6+y0;
   cout<<x1<<"                "<<y1<<endl;
   x0=x1;
   y0=y1;
 }
}
double f(double x,double y)
{
 double w;
 w=y-2*x/y;
 return w;
}