def test_sign(self):
x = cp.Variable()
problem = cp.Problem(cp.Minimize(cp.sign(x)), [-2 <= x, x <= -0.5])
problem.solve(SOLVER, qcp=True)
self.assertEqual(problem.objective.value, -1)
self.assertLessEqual(x.value, 0)
problem = cp.Problem(cp.Maximize(cp.sign(x)), [1 <= x, x <= 2])
problem.solve(SOLVER, qcp=True)
self.assertEqual(problem.objective.value, 1.0)
self.assertGreater(x.value, 0)
def test_sign(self) -> None:
x = cp.Variable()
problem = cp.Problem(cp.Minimize(cp.sign(x)), [-2 <= x, x <= -0.5])
problem.solve(SOLVER, qcp=True)
self.assertEqual(problem.objective.value, -1)
self.assertLessEqual(x.value, 0)
problem = cp.Problem(cp.Maximize(cp.sign(x)), [1 <= x, x <= 2])
problem.solve(SOLVER, qcp=True)
self.assertEqual(problem.objective.value, 1.0)
self.assertGreater(x.value, 0)
# Check that sign doesn't change value.
vector = np.array([.1, -.3, .5])
variable = cp.Variable(len(vector))
problem = cp.Problem(cp.Maximize(vector @ variable),
[cp.norm2(variable) <= 1.])
problem.solve()
value = variable.value.copy()
cp.sign(variable).value
self.assertItemsAlmostEqual(value, variable.value)
