Different values in ga variables.

Hello everybody. I'm trying to implement an algorithm that minimize Delta_V for an interplanetary mission. My professor would be that I use ga routine. I have a problem with 6 variables with two linear constraints, like x(1)=x(4) and x(2)=x(5). Now, I wrote my code and I think that's correct (I'm not so sure) but I have a problem with the 6 variables. Every time that I start the code the result is the same for Delta_V (It's ok) but the variables always change (a lot !!). I wrote Upper limit and Lower limit but the result doesn't change. This 6 variables are important because I must use them to create another code. What can I do?

Thank you in advance.

[Chad Greene]

I'm not familiar with the term ga. Can you please define it? In addition to clearly defining the goal, I think it will help if you can upload enough code for us to replicate the problem.

[Alessandro Novero]

ga is genetic algorithm routine of the optimization toolbox .

Answer 1

[Alan Weiss]

If your objective function is smooth, you should not use ga, but instead use fmincon starting from a variety of initial points, perhaps by using MultiStart.

If your objective function is not smooth, use patternsearch starting from a variety of initial points as suggested here.

If your objective function is given by a simulation or solution of an ordinary differential equation, see Optimizing a Simulation or ODE for suggestions and caveats, especially about choosing larger finite difference steps in fmincon.

Good luck,

Alan Weiss

MATLAB mathematical toolbox documentation