Merge pull request #3422 from jsiirola/xpress-typo

xpress_direct: resolve error retrieving reduced costs

pyomo/solvers/plugins/solvers/xpress_direct.py

@@ -1126,7 +1126,7 @@ def _load_rc(self, vars_to_load=None):
             vars_to_load = var_map.keys()
 
         xpress_vars_to_load = [var_map[pyomo_var] for pyomo_var in vars_to_load]
-        vals = self._getRedCost(self._solver_model, xpress_vars_to_load)
+        vals = self._getRedCosts(self._solver_model, xpress_vars_to_load)
 
         for var, val in zip(vars_to_load, vals):
             if ref_vars[var] > 0:

pyomo/solvers/tests/checks/test_xpress_persistent.py

@@ -40,10 +40,23 @@ def test_basics(self):
         res = opt.solve()
         self.assertAlmostEqual(m.x.value, -0.4, delta=1e-6)
         self.assertAlmostEqual(m.y.value, 0.2, delta=1e-6)
+
         opt.load_duals()
+        self.assertEqual(len(m.dual), 1)
         self.assertAlmostEqual(m.dual[m.c1], -0.4, delta=1e-6)
         del m.dual
 
+        opt.load_rc()
+        self.assertEqual(len(m.rc), 2)
+        self.assertAlmostEqual(m.rc[m.x], 0, delta=1e-8)
+        self.assertAlmostEqual(m.rc[m.y], 0, delta=1e-8)
+        del m.rc
+
+        opt.load_slacks()
+        self.assertEqual(len(m.slack), 1)
+        self.assertAlmostEqual(m.slack[m.c1], 0, delta=1e-6)
+        del m.slack
+
         m.c2 = pe.Constraint(expr=m.y >= -m.x + 1)
         opt.add_constraint(m.c2)
         self.assertEqual(opt.get_xpress_attribute('cols'), 2)