  We present the first results from BlackHat, an automated C++ program for
calculating one-loop amplitudes. The program implements the unitarity method
and on-shell recursion to construct amplitudes. As input to the calculation, it
uses compact analytic formulae for tree amplitudes for four-dimensional
helicity states. The program performs all related computations numerically. We
make use of recently developed on-shell methods for evaluating coefficients of
loop integrals, introducing a discrete Fourier projection as a means of
improving efficiency and numerical stability. We illustrate the numerical
stability of our approach by computing and analyzing six-, seven- and
eight-gluon amplitudes in QCD and comparing against previously-obtained
analytic results.
