Initializing the auxiliary gurobi variables

Answered

Ramesh singh

• February 28, 2023 11:23

Hi, 

     i am using t3[j,i] as auxiliary variable, i need to initialize it with zero. This variable t3 is updated using constraints when optimized variable C  is set. I am sharing here partial code where CR and data are the input (python variable). Please help me whether this is the correct way or not thank you.  

t3=m.addVars(range(1,R+1),range(1,P+1),vtype=GRB.CONTINUOUS,name="t3")

C=m.addVars(range(1,P+1),range(1,M+1),lb=0,ub=1,vtype=GRB.BINARY, name="C")

for j in range(1,R+1):
    for i in range(1,P+1):
        t3[j,i].START=0

for i in range(1,P+1):
    for k in range(1,M+1):
        m.addConstr((C[i,k]==1) >> (t3[CR[k],i]==data[i]))

Related to

• MIPStart

0

• 

  Matthias Miltenberger

  Gurobi Staff

  • February 28, 2023 12:55

  Hi Ramesh,

  You don't have to initialize variables. Gurobi will anyway try the zero solution and check whether this is feasible. The START attribute really makes sense when you have a valid (non-zero) starting solution available - even if it may only contain a subset of the variables. Then Gurobi will try to complete this solution and use it to have an initial primal bound to speed up the solving process.

  Please check out this guide on MIP Starts: How do I use MIP starts? – Gurobi Help Center

  I hope that helps.

  Cheers,
  Matthias

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