#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

int main()
{
      char    comments[256];
    int    i, j;
    double    J=0.0, dx=0.0, dv=0.0;
    double    load1=0.0, load2=0.0, load3=0.0, load4=0.0;
    double    *coord, *coord0, *coord1, *velocity, *velocity0, *velocity1;

    coord = (double *)malloc(1050*sizeof(double));
    coord0 = (double *)malloc(1050*sizeof(double));
    coord1 = (double *)malloc(1050*sizeof(double));
    velocity = (double *)malloc(1050*sizeof(double));
    velocity0 = (double *)malloc(1050*sizeof(double));
    velocity1 = (double *)malloc(1050*sizeof(double));

    FILE    *pp1, *pp2;
    pp1=fopen("1129-5000.velS", "r");
    pp2=fopen("pengzhuanghousudu.dat", "w");   

    for( i=0; i<1050; ++i ){
            fscanf(pp1, "%lf %lf %lf %lf", &load1, &load2, &load3, &load4);
        coord0[i]=load1;
        coord1[i]=load2;
        coord[i]=sqrt(coord0[i]*coord0[i]+coord1[i]*coord1[i]);
        velocity0[i]=load3;   
        velocity1[i]=load4;   
        velocity[i]=sqrt(velocity0[i]*velocity0[i]+velocity1[i]*velocity1[i]);
    }

    for(i=0;i<1050-1;++i){
        for(j=i+1;j<1050;++j){
            dx=coord[j]-coord[i];
            dv=velocity[j]-velocity[i];
            J=-1.9*2650.0*2650.0/(2650.0+2650.0)*dv+0.4*1.9*2650.0*2650.0/(2650.0+2650.0)*dv;

            if(dx<0.00015){
                velocity0[i]+=J/2650.0;
                velocity1[i]+=J/2650.0;
                velocity0[j]-=J/2650.0;
                velocity1[j]-=J/2650.0;
            }
        }
    }
   
    coord0[i]=velocity0[i]*0.000005;
    coord1[i]=velocity1[i]*0.000005;
    coord0[j]=velocity0[j]*0.000005;
    coord1[j]=velocity0[j]*0.000005;

    strcpy( comments, "TITLE = \"velocity of sand\"" );   fprintf(pp2, "%s\n", comments);
    strcpy( comments, "VARIABLES = \"X\",\"Y\",\"x-velocity\", \"y-velocity\"" );fprintf(pp2, "%s\n", comments);
    strcpy( comments, "ZONE I=105,J=10,F=point\n" ); fprintf(pp2, "%s", comments);

    for(i=0;i<1050;i++){
        fprintf(pp2, "%e    %e     %e    %e\n", coord0[i], coord1[i], velocity0[i], velocity1[i]);
    }

    fclose(pp1);
    fclose(pp2);
}

咋了？怎么没人回答我，是我说的不清楚吗？

主要是代码觉得太复杂，想要实现什么功能?

表示无奈

我这里没错