I'm trying to get the coordinates of a 9x9 flat grid. The first point start at the origin. The current code has output but is apparently wrong.

Code:

#include<math.h>
#include<stdio.h>
#define pi 3.1415926
double initial( int Nbead, double Rold[3][Nbead],int Nx)
{int i;
for (i=0;i<Nbead;i++){
Rold[0][i] = (floor(i/Nx)-1)+1;
Rold[1][i] = (i%Nx);
Rold[2][i] = 0.0;
}
return Rold[3][Nbead];
}
int main()
{
int Nx=9;
int Ny=9;
double aa=1;
int Nbead=Nx*Ny; /*total number of beads*/
double Rold[3][Nbead];
int Nbond=2*Nx*Ny-Nx-Ny;/*total number of bonds*/
int j,k;
/*get the position (a flat sheet)*/
double initial(int Nbead, double Rold[3][Nbead],int Nx);
for (k=0;k<Nbead;k++)
{
for (j=0;j<3;j++)
printf("the j is %d, the k is %d, Rold is %d\n",j, k,Rold[j][k]);
printf("\n");
}
return 0;
}