  We test the hypothesis that the initial mass function (IMF) is determined by
the density probability distribution function (PDF) produced by supersonic
turbulence. We compare 14 simulations of star cluster formation in 50 solar
mass molecular cloud cores where the initial turbulence contains either purely
solenoidal or purely compressive modes, in each case resolving fragmentation to
the opacity limit to determine the resultant IMF. We find statistically
indistinguishable IMFs between the two sets of calculations, despite a factor
of two difference in the star formation rate and in the standard deviation of
$\log(\rho)$. This suggests that the density PDF, while determining the star
formation rate, is not the primary driver of the IMF.
