Riley Clement

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Activity overview

Latest activity by Riley Clement
  • Riley Clement commented,

    Hi Jan, I won't guarantee the details are correct - that is for you to check - but you have the general idea of translating the objective into something that can be used with Gurobi correct.  Gener...

  • Riley Clement commented,

    Hi Apostolos, I suspect most answers would be subjective.  My own opinion is that Matlab does not come close to the flexibility and expressiveness of Python.  Very few of our customers use Matlab, ...

  • Riley Clement commented,

    Hi Wenjia, From a quick glance it looks like the issue is this: \[\left\| \begin{bmatrix} a + b \\ c \end{bmatrix}  \right\|^2 = (a+b)^2 + c^2\] \[\left\| \begin{bmatrix} a + b \\ c \end{bmatrix}  ...

  • Riley Clement commented,

    Hi Tanay, My advice is to write your model to a LP file, and open the file in a text editor.  You will want to verify that the constraint you believe to be violated is present in the model.  You ca...

  • Riley Clement commented,

    Hi Wenjia, I don't understand why an SOCP would be considered non-convex I think we'd need to see the code to be able to comment further.  Feel free to drop a link to file in DropBox, Google Driv...

  • Riley Clement commented,

    This may also come down to the implementation in the code.  For example, this is convex: m = gp.Model()x = m.addVar()y = m.addVar()m.setObjective(x**2 + y**2, gp.GRB.MINIMIZE)m.optimize() We tend t...

  • Riley Clement commented,

    It may also be useful to look at a paper showing different formulations for single machine scheduling.  This looks more like a modelling problem than a java problem.Keha, Ahmet B., Ketan Khowala, a...

  • Riley Clement commented,

    Yes, dual values cannot be extracted when there are integer variables. Some users get dual values for MIPs following the method outlined in the below article (although it generally doesn't make sen...

  • Riley Clement commented,

    HI Shahin, Can you check the model is solved to optimality and does not contain integer (including binary) variables? - Riley  

  • Riley Clement commented,

    Hi Sibo, It's fairly typical to have trouble closing the gap on a model with nonconvex quadratic constraints. I would certainly start with default parameters and only change values if there is sub...