Fix GSLS optimizer bounds if entries have None (#95)

qiskit_algorithms/optimizers/gsls.py

@@ -119,8 +119,8 @@ def minimize(
             var_lb = np.array([-np.inf] * x0.size)
             var_ub = np.array([np.inf] * x0.size)
         else:
-            var_lb = np.array([l for (l, _) in bounds])
-            var_ub = np.array([u for (_, u) in bounds])
+            var_lb = np.array([l if l is not None else -np.inf for (l, _) in bounds])
+            var_ub = np.array([u if u is not None else np.inf for (_, u) in bounds])
 
         x, fun_, nfev, _ = self.ls_optimize(x0.size, fun, x0, var_lb, var_ub)
 

releasenotes/notes/fix_gsls_bounds-29d4a7506130cd69.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes :class:`.GSLS` optimizer :meth:`~.GSLS.minimize` so that if the ``bounds`` parameter
+    is passed with tuples that have entries of ``None`` then the entry is treated
+    as equivalent to infinity.

test/optimizers/test_optimizers.py

@@ -160,6 +160,13 @@ def test_gsls(self):
         self.assertLessEqual(x_value, 0.01)
         self.assertLessEqual(n_evals, 10000)
 
+        with self.subTest("Bounds (None, None)"):
+            algorithm_globals.random_seed = 1
+            res = optimizer.minimize(rosen, x_0, bounds=[(None, None)] * len(x_0))
+
+            self.assertLessEqual(res.fun, 0.01)
+            self.assertLessEqual(res.nfev, 10000)
+
     def test_scipy_optimizer(self):
         """scipy_optimizer test"""
         optimizer = SciPyOptimizer("BFGS", options={"maxiter": 1000})