Relative error of the sink particle mass in collapsing isothermal sphere simulations with two different accretion schemes. We examine two values of A (2.2, 4.0) in Table 1 of Shu (1977) and an extreme case (90) where the mean gas density inside the accretion zone is similar to ρ_th. The lines with different colors represent the results of runs with different accretion radii, as indicated in the legend. The flux and Bondi-Hoyle accretion runs are shown as solid and dashed lines, respectively.