direct template fluxes to determine $U-V$. When using closely-spaced medium-band observed filters, the template fluxes are found to be more robust than interpolating between observed filters (see Brammer et al. 2010, in prep.).

SED Modeling {#subsec-sed}
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Stellar masses and other stellar population parameters were determined with FAST [@kriek09a], fixing the redshift to the EAZY output (or the spectroscopic redshift when available). For consistency with previously published SMF measurements and straightforward comparisons, we assumed the default SED-modeling assumptions of @marchesini09, i.e., stellar population synthesis models of @bruzual03, the @calzetti00 reddening law with $A_{\rm V}$ values ranging from 0 to 4 in step of 0.2 mag, solar metallicity, pseudo-@kroupa01[^4] initial mass function (IMF), and three star formation histories (SFHs): a single stellar population (SSP), a constant star formation history (CSF), and an exponentially declining SFH with an e-folding timescale of 300 Myr ($\tau_{300}$). In order to quantify the systematic uncertainties due to different SED-modeling assumptions on the derived stellar population properties (i.e., $M_{\rm star}$, age, star formation rate, and $A_{\rm V}$) of the $3.0\leq z < 4.0$ sample, we have also assumed the stellar population synthesis models of @maraston05 with a @kroupa01 IMF and exponentially declining star formation histories with values 