Write a function of the below prototype in ``physics.c'' which computes the quantity
where 
represents the filling of each of the states.
void getRho(double *Rho, double ***Psi, double **F, int lmax, int *nmax, int N)Output:
- Rho[k]:
for all grid points r[k]
Input:
- Psi[l][n][k]: values of normalized
- F[l][n]: shell occupancies
- lmax: maximum angular momentum to consider (l=0 through l=lmax)
- nmax[l]: maximum number of nodes sought for angular momentum l
- N: number of intervals for the grid