The Initial Mass Function (IMF) is an empirical density/mass-style function that describes the distribution of initial masses of stars. It is typically given as N(m)dm.
Edwin Salpeter developed an early IMF in 1955, the Salpeter function:
N(m)dm = C × (m/MSun)-2.35(dm/MSun)
C is a constant reflecting local stellar density.
Dense Core Mass Function (DCMF)
Stellar Population Synthesis Code