Thank you for the reply, Alan. I am ashamed to admit I can make no head or tail of it. Integer-constrained solver = the constraint I set through optim.intcon? In my case, optim.intcon = 1, and the first parameter in optim.options.InitialPopulationMatrix is 44. The fitness function cannot operate with anything other than an integer for x(1).
What is the difference between a problem structure and the "struct" I used for my problem? Again, sorry, I could not make the difference from the documentation page you directed me to. I picked up the syntax I posted after searching for the recommended ways to pass extra variables to the fitness function used by GA.