  Fitting complicated models to large datasets is a bottleneck of many
analyses. We present GooFit, a library and tool for constructing
arbitrarily-complex probability density functions (PDFs) to be evaluated on
nVidia GPUs or on multicore CPUs using OpenMP. The massive parallelisation of
dividing up event calculations between hundreds of processors can achieve
speedups of factors 200-300 in real-world problems.
