Suyue Xu

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Activity overview

Latest activity by Suyue Xu

  • Suyue Xu commented,

    1. Community
    2. Algorithms
    3. BestBd of MILP hardly moves

    Hi Riley Thank you for your suggestion!I tried to run the NoRel heuristic for 1200s,and it turns out shifting to phase 2 quickly.Here is the log: Set parameter UsernameSet parameter CrossoverBasis ...

  • Suyue Xu commented,

    1. Community
    2. Algorithms
    3. BestBd of MILP hardly moves

    as the big-M method is introduced to solve the C&CG subpoblem,I'm wondering if the value of constant M could make any difference.So I changed the constant value from 10^6 to 10^4,here is the log : ...

  • Suyue Xu created a post,

    BestBd of MILP hardly moves

    Answered
    1. Community
    2. Algorithms

    Hello everyone I'm dealing with a MILP model functioning as the subproblem of column and constraint generation algorithms(C&CG).However gurobi struggles to push the BestBd of the model.I've tried t...

    • Suyue Xu
    • 2 followers
    • 4 comments
    • 0 votes

  • Suyue Xu created a post,

    wrong solution due to numeric issues

    Awaiting user input
    1. Community
    2. Algorithms

    Hi gurobi support team I find a wrong solution due to numeric issues with the warning:'Warning: 1 variables dropped from basis'.Here is the log: Set parameter UsernameSet parameter TimeLimit to val...

    • Suyue Xu
    • 2 followers
    • 1 comment
    • 0 votes

  • Suyue Xu commented,

    1. Community
    2. Algorithms
    3. gurobi struggles to narrow the gap of MIP

    Thank you for your advice!

  • Suyue Xu commented,

    1. Community
    2. Algorithms
    3. gurobi struggles to narrow the gap of MIP

    Hi Riley I've tried to experiment with MIPFocus and Cuts to set them to 3,and try different branch direction,but all these measures make no difference.What do you mean by "improving the lower bound...

  • Suyue Xu created a post,

    gurobi struggles to narrow the gap of MIP

    Answered
    1. Community
    2. Algorithms

    Hi gurobi support team  I'm now solving a MIP problem with quardratic objectives and linear constraints(along with PWL constraints).The result shows that gurobi quickly narrwo the gap to less than ...

    • Suyue Xu
    • 2 followers
    • 4 comments
    • 0 votes

  • Suyue Xu commented,

    1. Community
    2. Algorithms
    3. How to speed up MILP model to find the solution?

    Hi Jaromil Unfortunately the MILP model can find a solution in less than 10 min,but i'm still not satisfied with the efficiency.After I revised problems you mentioned above, it seems that the heuri...

  • Suyue Xu commented,

    1. Community
    2. Algorithms
    3. How to speed up MILP model to find the solution?

    Thank you, Jaromil I will try to clean up very small coefficients and pay attention to the numeric issues.Thank you for your kindly comment again!

  • Suyue Xu commented,

    1. Community
    2. Algorithms
    3. How to speed up MILP model to find the solution?

    Thank you for your comment! It seems that the model has numerical issues, as the binary variables could oscilate during the branch-and-bound.Here is the possible problem syntax(written in MATLAB wi...