Questions for the Gillespie DT paper

Q1 If a chemically reacting system is given with N species and M reaction channels, estimate the corresponding computational complexity of the SSA, the tau-leaping and the explicit Euler methods in N and M.

Q2 Write codes (in C, C++ or Fortran) for the SSA, tau-leaping methods for discrete chemically reacting model and explicit Euler method for a set of ODEs. Try your codes on the decaying dimerization model in this paper. Modify the initial populations of X1, X2 and X3. What range of the population values should be in such that the tau-leaping method has efficiency advantages than the SSA and the explicit Euler method?