How do I optimize a function?

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Answer 1

[Star Strider]

The optimisation routines need vector input for the parameters. I combine them as vector ‘p’ here.

Try this:

x0 = [0.5; 500];
[x, fval] = fmincon(@(p) -launch(p(1),p(2)), x0, [],[],[],[], [0.11 15], [1 1310])

Note that the optimisation functions minimise the function output, so to maximise it, you need to negate the the function.

When I ran your function, I got:

x =
   893.8695e-003
   473.4764e+000

fval =
   -38.4141e+000

So ‘m2=0.89’, ‘k2=473’, producing a distance of 38.4.

You may need to experiment to get the result you want. See the documentation for fmincon for details on what it can do.

[Star Strider]

Walle Walhood’s Answer moved here —

So, the fval is a negative number.? is there a way to limit the output make sure it is a positive number?

Also, thank you very much for your help

[Star Strider]

My pleasure.

Since I negated the function in order to maximise it, fval will be negative. Just remove the minus sign to get the correct result.

If my Answer helped you solve your problem, please Accept it!

Answer 2

[Walle Walhood]

I sure will, Thanks again!

[Star Strider]

As always, my pleasure!

Also, you can run your function with the optimised variables to get the ‘positive’ distance.