def test_maximize_to_minimize(self):
"""Test maximization to minimization conversion"""
op_max = QuadraticProgram()
op_min = QuadraticProgram()
for i in range(2):
op_max.binary_var(name="x{}".format(i))
op_min.binary_var(name="x{}".format(i))
op_max.integer_var(name="x{}".format(2), lowerbound=-3, upperbound=3)
op_min.integer_var(name="x{}".format(2), lowerbound=-3, upperbound=3)
op_max.maximize(constant=3,
linear={"x0": 1},
quadratic={("x1", "x2"): 2})
op_min.minimize(constant=3,
linear={"x0": 1},
quadratic={("x1", "x2"): 2})
# check conversion of maximization problem
conv = MaximizeToMinimize()
op_conv = conv.convert(op_max)
self.assertEqual(op_conv.objective.sense,
op_conv.objective.Sense.MINIMIZE)
x = [0, 1, 2]
fval_min = op_conv.objective.evaluate(conv.interpret(x))
self.assertAlmostEqual(fval_min, -7)
self.assertAlmostEqual(op_max.objective.evaluate(x), -fval_min)
# check conversion of minimization problem
op_conv = conv.convert(op_min)
self.assertEqual(op_conv.objective.sense, op_min.objective.sense)
fval_min = op_conv.objective.evaluate(conv.interpret(x))
self.assertAlmostEqual(op_min.objective.evaluate(x), fval_min)
def test_minimization_problem(self):
"""Tests the optimizer with a minimization problem"""
optimizer = GoemansWilliamsonOptimizer(num_cuts=10, seed=0)
problem = Maxcut(self.graph).to_quadratic_program()
# artificially convert to minimization
max2min = MaximizeToMinimize()
problem = max2min.convert(problem)
results = optimizer.solve(problem)
np.testing.assert_almost_equal([0, 1, 1, 0], results.x, 3)
np.testing.assert_almost_equal(4, results.fval, 3)