不懂哦,这东西真是无聊

#include   "stdio.h"
#include   "math.h"
#define   A   0                                       /*定义初值和步长*/
#define   B   0.002
#define   C   1
#define   D   1
#define   E   1
double   f(double,double,double,double);                 /*   定义函数*/
double   g(double,double,double,double);
double   e(double,double,double,double);
main()
{
    double x0=A, h=B, y01=C, u01=D, v01=E,
    double jn[4], kn[4], ln[4];        /*  j01 -- j04   k01 -- k04  l01 -- l04  */
    int   i,n=10000;
    FILE   *cfPtr;
    if((cfPtr=fopen("luolunzi.dat","w"))==NULL)                     /*数据要写入的文件*/
    printf("File   could   not   be   opened\n");
    else
    {   
    for   (i=1;i <=n;i++)
      {                                                                                               /*套用公式开始计算*/   
        x0=x0+h;
        jn[0]=f(x0,y01,u01,v01);
        kn[0]=g(x0,y01,u01,v01);
        ln[0]=e(x0,y01,u01,v01);
      
        jn[1]=f(x0+h/2.0,y01+h/2.0*jn[0],u01+h/2.0*kn[0],v01+h/2.0*ln[0]);
        kn[1]=g(x0+h/2.0,y01+h/2.0*jn[0],u01+h/2.0*kn[0],v01+h/2.0*ln[0]);
        ln[1]=e(x0+h/2.0,y01+h/2.0*jn[0],u01+h/2.0*kn[0],v01+h/2.0*ln[0]);
        jn[2]=f(x0+h/2.0,y01+h/2.0*jn[1],u01+h/2.0*kn[1],v01+h/2.0*ln[1]);
        kn[2]=g(x0+h/2.0,y01+h/2.0*jn[1],u01+h/2.0*kn[1],v01+h/2.0*ln[1]);
        ln[2]=e(x0+h/2.0,y01+h/2.0*jn[1],u01+h/2.0*kn[1],v01+h/2.0*ln[1]);
         
        jn[3]=f(x0+h,y01+h*jn[1],u01+h*kn[1],v01+h*ln[1]);
        kn[3]=g(x0+h,y01+h*jn[1],u01+h*kn[1],v01+h*ln[1]);
        ln[3]=e(x0+h,y01+h*jn[1],u01+h*kn[1],v01+h*ln[1]);
      
        y01=y01+h/6.0*(jn[0]+2.0*jn[1]+2.0*jn[2]+jn[3]);
        u01=u01+h/6.0*(kn[0]+2.0*kn[1]+2.0*kn[2]+kn[3]);
        v01=v01+h/6.0*(ln[0]+2.0*ln[1]+2.0*ln[2]+ln[3]);
        
        printf("%15.7f\t%15.7f\t%15.7f\t\n",x0,y01,u01,v01);
        fprintf(cfPtr,"%15.7f\t%15.7f\t%15.7f\t\n",x0,y01,u01,v01);
        }
      fclose(cfPtr);
}
}   
double   f(double   s1,double   q1,double   u1,double   r1)                         /*定义的微分方程*/     
{
      double   z1;
      z1=-10*q1+(10*u1);
      return   z1;
}
double   g(double   s2,double   q2,double   u2,double   r2)
{
      double   z2;
      z2=28*q2-u2-q2*r2;
      return   z2;
}
double   e(double   s3,double   q3,double   u3,double   r3)
{
double   z3;
z3=(-8/3)*r3+q3*u3;
return   z3;
}