Gurobi python negative equality constraints and infeasible solution

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Habeeb P

2022年08月02日 15:14 編集済み

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Hi,

I have been trying to understand the gurobi python API. The following program outputs the maximum value, but if I change the x==1 constraint to x==-1, the program outputs, "Model is infeasible or unbounded."

Please help me to solve the issue.

import gurobipy asgp

from gurobipy import GRB

import math

m = gp.Model("model1")

# Create variables

x = m.addVar(name="x")

y = m.addVar(name="y")

z = m.addVar(name="z")

xp0 = m.addVar(name="xp0")

yp0 = m.addVar(name="yp0")

zp0 = m.addVar(name="zp0")




obj = ((xp0 - x)**2 + (yp0 - y)**2 + (zp0 - z)**2)

# m.setObjective(obj, GRB.MINIMIZE)

m.setObjective(obj, GRB.MAXIMIZE)
m.addConstr(x == 1, "c0")

m.addConstr(y == 0, "c1")

m.addConstr(z == 10, "c2")

m.addConstrs(xp0 <= 1, "qc0")

m.addConstr(xp0 >= -1, "qc1")

m.addConstr(yp0 <= 1, "qc2")

m.addConstr(yp0 >= -1, "qc3")

m.addConstr(zp0 <= 1, "qc4")

m.addConstr(zp0 >= -1, "qc5")

m.optimize()

forvinm.getVars():

  print('%s%g' % (v.VarName, v.X))

print('Obj: %g' % obj.getValue())

0

• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2025年11月16日 23:31

  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 try Gurobot, our chatbot interface offering instant, expert-level support.
• 

  Eli Towle

  • Gurobi Staff

  2022年08月02日 19:50

  By default, variables added to the model via Model.addVar() or Model.addVars() have a lower bound of 0. To resolve the issue, change the lower bound on \( \texttt{x} \). For example:

  x = m.addVar(lb=-GRB.INFINITY, name="x")

  1

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