Np_final, xp, rp, V, Rve, Rg, eps_agg = ptsa(Np, mean_rp, rel_std_rp, Df, k, max_search_num, rng)

==== Input parameters ===
Np: number of monomers
mean_rp: mean of the normal distribution of the monomer radius
rel_std_rp: relative standard deviation of the normal distrituion of the monomer radius 
Df: fractal dimension
k: fractal prefactor
max_search_num: maximum number of iteration for searching a location of each monomer attached onto the surface of an aggregate 
rng: random number generator constructed by the numpy.random.default_rng()

=== Output variables ===
Np_final: number of monomers in the generated aggregate. If the aggregate generation failed, Np_final < Np.
xp: (x,y,z) coordinate of the center of individual monomers relative to the centroid of the aggregate. 2D of shape= (Np,3).
rp: radii of individual monomers. 1D array of size= Np.
V: volume of the aggregate.
Rve: volume-equivalent radius of the aggregate.
Rg: gyration radius of aggregate.
eps_agg: porosity of the aggregate calculated using the gyration method (cf. Singh PhD thesis, 2021).