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pythonsolverpyomo

Pyomo with glpk solver doesn't solve anything

Shouldn't the following result in a number different than zero?

import pyomo.environ as pyo
from pyomo.opt import SolverFactory

m = pyo.ConcreteModel()
m.x = pyo.Var([1,2], domain=pyo.Reals,initialize=0)
m.obj = pyo.Objective(expr = 2*m.x[1] + 3*m.x[2],sense=pyo.minimize)
m.c1 = pyo.Constraint(expr = 3*m.x[1] + 4*m.x[2] >= 3)
SolverFactory('glpk', executable='/usr/bin/glpsol').solve(m)
pyo.value(m.x[1])

I have tried following the documentation but its quite limited for simple examples. When I execute this code it just prints zero...

Solution

  • The problem you have written is unbounded. Try changing the domain of x to NonNegativeReals or put in constraints to do same.

    You should always check the solver status, which you seem to have skipped over and will state “unbounded” for this model.