下面的程序运行800多部的时候出现错误,请帮忙确认一下


#include "stdio.h"
#include "math.h"
#include<graphics.h>
   #include<conio.h>



void fun(double y[4],double d[4])
{
    d[0]=(0.01-y[0]-2*((y[2]>0)?y[2]:0)+5-2.5*y[1])/2;
    d[1]=(0-y[1]+((y[0]>0)?y[0]:0))/12;
    d[2]=(0-y[2]-2*((y[0]>0)?y[0]:0)+5-2.5*y[3])/2;
    d[3]=(0-y[3]+((y[2]>0)?y[2]:0))/12;
}

void rkg(double h,double y[4],double d[4])
{
   
     double a21=h/2;
     double a31=(sqrt(2.0)-1)/2*h;
     double a32=(2-sqrt(2.0))/2*h;

     double a42=-sqrt(2.0)/2*h;
     double a43=(2+sqrt(2.0))/2*h;

     double b1=1*h/6;
     double b2=(2-sqrt(2.0))*h/6;
     double b3=(2+sqrt(2.0))*h/6;
     double b4=1*h/6;


     double k1[4],k2[4],k3[4],k4[4];
     double temp_y[4];
     int i=0;
     for(i=0;i<4;i++)
         temp_y[i]=y[i];
     fun(temp_y,k1);

     for(i=0;i<4;i++)
         temp_y[i]=y[i]+a21*k1[i];
     fun(temp_y,k2);

     for(i=0;i<4;i++)
         temp_y[i]=y[i]+a31*k1[i]+a32*k2[i];
     fun(temp_y,k3);

     for(i=0;i<4;i++)
         temp_y[i]=y[i]+a42*k2[i]+a43*k3[i];
     fun(temp_y,k4);

     for(i=0;i<4;i++)
         d[i]=y[i]+b1*k1[i]+b2*k2[i]+b3*k3[i]+b4*k4[i];
 }
void main()
{        FILE *fp;
     int i;
    double t,h,z[1000][5];
    z[0][1]=0.0; z[0][2]=0.0; z[0][3]=0.0;z[0][0]=0.0;
    t=0.0;h=0.05;

    for(i=0;i<1000;i++)
        {
         rkg(h,z[i],z[i+1]);
             fprintf(fp,"%f,%f,%f,%f,%f\n",t+h*i,z[i][0],z[i][1],z[i][2],z[i][3]);
                 }
    for(i=0;i<1000;i++)
    {printf("%f,%f,%f,%f,%f\n",t+h*i,z[i][0],z[i][1],z[i][2],z[i][3]);
/*getch();*/}

}
void graph()
{
int gdrive,gmode=VGAHI;
gdrive=VGA;
initgraph(&gdrive,&gmode,"d:\tc20");

closegraph();
}

#include<graphics.h> 什么意思

输出图像用的