Fitness function increases rather than decreasing with fmincon using hybrid Genetic Algorithm

While running a hybrid GA with fmincon for minimising the objective function to 0. Once GA stops and fmincon starts. The fitness value in iteration as shown in figure instead of decreasing increases. GA achieves perfect solutions, but with fmincon usage approximate solution is obtained. I am using interior algorithm with central difference in fmincon. Note this code is related to my topic. For standard bencmark problems the process works just fine .

Answer 1

[Matt J]

This might happen if your objective has discontinuities or non-differentiabilities. Such functions are outside the scope of fmincon.

[Ankur Shah]

Hey Matt,

It might be an issue. When using GA with fminunc and even fminsearch, both the functions can't decrease the fitness function any further than that by GA. Is there anything which can be done to minimize further?

[Matt J]

Is there anything which can be done to minimize further

Not if GA has already successfully brought you to the global minimum. If so, then there's no further to go.