这个程序是龙格库塔法 4阶乘的源程序  小弟实在是看不明白
void rk(t,y,n,h,k,z,f)
void (*f)();
int n,k;
double t,h,y[],z[];
{
    int i,j,l;
    double a[4],tt,*b,*d;
    b=malloc(n*sizeof(double));
    d=malloc(n*sizeof(double));
    a[0]=h/2.0;a[1]=a[0];
    a[2]=h;a[3]=h;
    for (i=0;i<=n-1;i++) z[i*k]=y[i];
    for (l=1;l<=k-1;l++)
      {
       (*f)(t,y,n,d);
       for(i=0;i<=n-1;i++) b[i]=y[i];
       for(j=0;j<=2;j++)
        {
            for(i=0;i<=n-1;i++)
           {
            y[i]=z[i*k+l-1]+a[j]*d[i];
            b[i]=b[i]+a[j+1]*d[i]/3.0;
           }
          tt=t+a[j];
         (*f)(tt,y,n,d) ;
        }
      for (i=0;i<=n-1;i++)
        z[i*k+l]=y[i];
      t=t+h;
     }
   free(b);free(d);
} 辛苦您了