Evolution and Optimum Seeking

218 Comparison of Direct Search Strategies for Parameter Optimization
by the storage capacity, taking the values 3, 10, 30, 100, 300, and 1000. Of course, if a
problem with, for example, 30 variables could not be solved by a strategy, or if no result
was forthcoming at the end of the maximum computation time of 8 hours, the number of
variables was not increased any further.
As in the rst test, the initial conditions were speci ed by
x (0)
i
Two exceptions are Problem 3.3 with
= x i + (;1)i
p n i = 1(1)n
x (0)
i = x i + (;1)i
10 p n
to ensure that the search always converged to the desired minimum and not to one of the
many others of equal value and Problem 3.10 with
x (0)
i = x i + 1
p n
to start the search within the feasible region. Problems 3.8 and 3.9, whose minima are at
in nity, required special treatment of the starting point and termination conditions (see
Appendix A, Sect. A.3).
The results are presented in Table 6.10. For comparison, some of the results of the
rst test (Problem 1.1) are also displayed. The numbers enable one to assess critically
on the one hand the reliability of a strategy and on the other the computation times it
requires.