Engineering Optimization: Theory and Practice, Fourth Edition

324 Nonlinear Programming II: Unconstrained Optimization Techniques

Figure 6.8 Progress of Powell’s method.

is stored as the vectorZin block A, and the pattern direction is constructed by sub-

tracting the previous base point from the current one in block B. The pattern direction

is then used as a minimization direction in blocks C and D. For the next cycle, the

first direction used in the previous cycle is discarded in favor of the current pattern

direction. This is achieved by updating the numbers of the search directions as shown

in block E. Thus both pointsZandXused in block B for the construction of pattern