Two parallel deterministic direct search algorithms are used to find improved
parameters for a system of differential equations designed to simulate the cell cycle of budding
yeast. Comparing the model simulation results to experimental data is difficult because most of
the experimental data is qualitative rather than quantitative. An algorithm to convert simulation
results to mutant phenotypes is presented. Vectors of parameters defining the differential equation
model are rated by a discontinuous objective function. Parallel results on a 2200 processor
supercomputer are presented for a global optimization algorithm, DIRECT, a local optimization
algorithm, MADS, and a hybrid of the two
