Different Dual values?

ユーザーの入力を待っています。

Sanjeev Bhurtyal

2021年09月19日 18:39

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Why do I get different dual values for the same problem when I use model.getAttr("Pi", constraint list) and model.getConstrbyName("Constraint Name").pi?

mdlSP = gurobipy.model("Problem")
#1st Formulation
for j in jc:
    for c in co:
        for t in tm:
            Supply[j,c,t] =mdlSP.addConstr((quicksum(ot[j,jdash,c,t]for jdash in jc)+
                            quicksum(cta[j]*cta[jdash]*orr[j,jdash,c,t]for jdash in jc)+
                            quicksum(EC[equ,c]*xt[j,i,c,t,equ]for i in ip  for equ in eq)+
                            quicksum((EC[equ,c]*pta[i]*cta[j]*xr[j,i,c,t,equ])for i in ip for equ in eq)<=
                            q[j,c,t]), name = "Supply_%s_%s_%s"%(j,c,t))

#Get Dual
mdlSP.getAttr('Pi',Supply)


#2nd Formulation
#Constraint:
for j in jc:
    for c in co:
        for t in tm:
            mdlSP.addConstr((quicksum(ot[j,jdash,c,t]for jdash in jc)+
                            quicksum(cta[j]*cta[jdash]*orr[j,jdash,c,t]for jdash in jc)+
                            quicksum(EC[equ,c]*xt[j,i,c,t,equ]for i in ip  for equ in eq)+
                            quicksum((EC[equ,c]*pta[i]*cta[j]*xr[j,i,c,t,equ])for i in ip for equ in eq)<=
                            q[j,c,t]), name = "Supply_%s_%s_%s"%(j,c,t))

#Get Dual
     for j in jc:
         for c in co:
             for t in tm:
                 nu[j,c,t] = mdlSP.getConstrByName("Supply_%s_%s_%s"%(jdash,c,t)).pi

0

• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2025年06月23日 02:47 編集済み

  This post is more than three years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum. Or why not try our AI Gurobot?.
• 

  Matthias Miltenberger

  • Gurobi Staff

  2021年09月20日 08:01

  Hi Sanjeev!

  Could you please try posting a minimal reproducible example (MRE)?

  Thanks,
  Matthias

   

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