The desirability functions and optimization are explained here.
The general description is:
Optimization Algorithm
Optimization of the overall desirability function, or of the single desirability function if there is only one response, is conducted as follows.
For categorical factors, a coordinate exchange algorithm is used.
For continuous factors, a gradient descent algorithm is used.
In the presence of constraints or mixture factors, a Wolfe reduced-gradient approach is used.
A detailed description is omitted because JMP software is proprietary.
I see. I try to understand the black box behind simulation because I faced a strange situation when I run simulation experiments a lot of times. (lets say doing run after run) JMP always suggests me different factor levels with smaller defect rates. The number of simulation runs I make is bigger, the better defect rate it suggests me. I don t understand these unstable optimization solutions. Why it does not suggest me global optimum factor levels, how many times do i rerun simulation to get global optimum?