Hello, I think there is an error in the termination of the Simplex optimization algorithm implemented by scipy.optimize.fmin(). According to the doc string, xtol and ftol are _relative_ values: xtol -- acceptable relative error in xopt for convergence. ftol -- acceptable relative error in func(xopt) for convergence. Yet, as I read the termination condition: if (max(Num.ravel(abs(sim[1:]-sim[0]))) <= xtol \ and max(abs(fsim[0]-fsim[1:])) <= ftol): break the values are taken as absolute quantities. Shouldn't the condition include some division of the difference by one of the values or a multiplication of the relative tolerances by one of the values for a proper relative comparison? Or, have I misinterpreted the statements above? Thanks, Michael Culbertson