
143Design Optimization
SOLUTION
In words, the above function asks for the minimum value of f(x) by choos-
ing the values of 40 decision variables, each of which can take six discrete
values. Clearly,
40
different solutions are possible, and their
corresponding objective values must be compared to find the best solu-
tion. If an enumeration takes 1 nanosecond (10
–9
seconds), the time it will
take to just enumerate the solutions is ×
0
14
years. This is more than the
estimated age of the universe! Problems of this magnitude are routinely
encountered in engineering. Fortunately, many times objective functions
give us properties that can ...