Using GALINI¶

Using GALINI as a command line tool¶

GALINI can be used as a command line tool to solve problems contained in a Python file. Let’s start with a Python file called pyomo_model.py with the following content:

import pyomo.environ as pe


def get_pyomo_model(*args, **kwargs):
    """ Returns an example Pyomo model. """
    m = pe.ConcreteModel()

    m.x = pe.Var(bounds=(0, None))
    m.y = pe.Var(bounds=(0, None))
    m.z = pe.Var(bounds=(0, None))

    m.obj = pe.Objective(expr=m.x, sense=pe.maximize)

    m.lin = pe.Constraint(expr=m.x + m.y + m.z == 1)
    m.soc = pe.Constraint(expr=m.x**2 + m.y**2 <= m.z**2)
    m.rot = pe.Constraint(expr=m.x**2 <= m.y * m.z)

    return m

We can solve it invoking GALINI as follows:

$ galini solve pyomo_model.py

After this, if everything was installed correctly, we can see the output:

Solution
Status
=======
optimal

       Objectives
Objective      Value
========================
obj         0.3269935604

       Variables
Variable      Value
=======================
x          0.3269935604
y          0.2570650583
z          0.4159413813

                             Counters
                       Name                              Value
==================================================================
elapsed_time                                         0.5653880000
time.branch_and_bound.find_initial_solution          0.0380930000
time.branch_and_cut.fbbt                             0.1714540000
time.branch_and_bound.solve_problem_at_root          0.2352560000
time.branch_and_cut.model_relaxation                 0.0165360000
time.branch_and_cut.obbt                             0.0942030000
time.branch_and_cut.try_solve_convex_model           0.0001600000
time.cuts_manager.before_start_at_root               0.0000050000
time.cuts_manager.solve_lower_bounding_relaxation    0.0537940000
branch_and_cut.cut_loop_iter                         1.0000000000
time.cuts_manager.after_end_at_root                  0.0000040000
time.branch_and_cut.solve_mip                        0.0451710000
time.branch_and_cut.update_node_branching_decision   0.0020380000
time.branch_and_cut.solve_upper_bounding_problem     0.1116560000
branch_and_bound.nodes_visited                       4.0000000000
branch_and_bound.lower_bound                         -0.3269935604
branch_and_bound.upper_bound                         -0.3269935604
branch_and_bound.relative_gap                        0.0000000000
branch_and_bound.relative_gap_integral               0.0090168144
time.branch_and_bound.solve_problem_at_node          0.2600030000
time.cuts_manager.before_start_at_node               0.0000100000
time.branch_and_cut.add_cuts_from_parent             0.0294750000
time.cuts_manager.after_end_at_node                  0.0000070000

The first three tables of the output (Status, Objectives, and Variables) contains the solution status, and the objective and variables values. The final table (Counters) shows the value of GALINI internal counters, for example the number of nodes visited and the elapsed time. These values are useful when measuring performance or debugging GALINI.

Using GALINI¶

Using GALINI as a command line tool¶

Using GALINI as a library¶