Difference between implementation and description of problem RE4-6-2

[salomonl]

Hey @ryojitanabe. Thank you for having coded the examples in different languages, it helped me a lot to debug my code which uses these examples.

There is a difference between the description of constraint g7 = 500000 - DWT in the supplementary material pdf and the way it is implemented for example in the c version or the python version. In this case, the constraint is g7 = 50000.0 -DWT. I took a look in the original implementation described in the original paper

Parsons, M. G., & Scott, R. L. (2004). Formulation of Multicriterion Design optimization Problems For Solution With Scalar Numerical Optimization Methods. Journal of Ship Research, 48(1), 61-76.

which corresponds to g7 = 500000 - DWT. Is there a reason for which you removed a 0 ?

Maybe another error of typo in the same problem. When I look at the equation S-100, I understand it as the fact that the annual_cargo variable is negative as annual_cargo = - CARGO_DWT * RTPA. Consequently, one user, when looking at the problem can think (it was my case) that f1 = annual_cost / annual_cargo is negative, which is not the case, as it is clarified by your implementation. The simplest will be to make the following correction: f3 = - annual_cargo = - CARGO_DWT * RTPA or -f3 = annual_cargo = cargo_dwt * RTPA.

Thank you again for having collected in the litterature this great set of real benchmarks !

[Ryoji Tanabe]

Thank you for pointing out the bug and the typo. I have fixed them.