Merge remote-tracking branch 'origin/negative_feature_10360' into neg…

…ative_feature_10360

10360.patch.txt

@@ -0,0 +1,66 @@
+diff --git a/qiskit/circuit/parameterexpression.py b/qiskit/circuit/parameterexpression.py
+index dc7614a30..71b9fb776 100644
+--- a/qiskit/circuit/parameterexpression.py
++++ b/qiskit/circuit/parameterexpression.py
+@@ -451,6 +451,17 @@ class ParameterExpression:
+
+             return self._call(_log)
+
++    def sign(self):
++        """Sign of a ParameterExpression"""
++        if _optionals.HAS_SYMENGINE:
++            import symengine
++
++            return self._call(symengine.sign)
++        else:
++            from sympy import sign as _sign
++
++            return self._call(_sign)
++
+     def __repr__(self):
+         return f"{self.__class__.__name__}({str(self)})"
+
+diff --git a/releasenotes/notes/added-sign-feature-parameterexpression-57693dd69103dc8c.yaml b/releasenotes/notes/added-sign-feature-parameterexpression-57693dd69103dc8c.yaml
+new file mode 100644
+index 000000000..b97382071
+--- /dev/null
++++ b/releasenotes/notes/added-sign-feature-parameterexpression-57693dd69103dc8c.yaml
+@@ -0,0 +1,18 @@
++---
++features:
++  - |
++    Added support for expressing the sign of a :class: 'ParameterExpression'
++    Instead of assigning a concrete value and using ''numpy.sign'' or other library functions, the user can use the instance of the ParameterExpression
++    class to calculate the sign and can work with the sign before the expression is fully assigned.
++
++    It can be used as follows::
++
++      from qiskit.circuit import Parameter
++
++      b = Parameter("phi")
++      sign_value = b.sign()
++      print("sign of an unassigned Parameter is: ", sign_value)
++      print("Sign of a Parameter assigned to -3 is: ", sign_value.assign(b,-3))
++
++    Refer to ' #10360<https://github.com/Qiskit/qiskit-terra/issues/10360>'__ for more details.
++
+diff --git a/test/python/circuit/test_parameters.py b/test/python/circuit/test_parameters.py
+index 31b73c55a..b74eef431 100644
+--- a/test/python/circuit/test_parameters.py
++++ b/test/python/circuit/test_parameters.py
+@@ -939,6 +939,15 @@ class TestParameters(QiskitTestCase):
+                 self.assertEqual(expected1, output1)
+                 self.assertEqual(expected2, output2)
+
++    def test_sign_of_parameter(self):
++        """Test returning the sign of the value of the parameter"""
++
++        b = Parameter("phi")
++        sign_of_parameter = b.sign()
++        self.assertEqual(sign_of_parameter.assign(b, -3), -1)
++        self.assertEqual(sign_of_parameter.assign(b, 2), 1)
++        self.assertEqual(sign_of_parameter.assign(b, 0), 0)
++
+     @combine(target_type=["gate", "instruction"], parameter_type=["numbers", "parameters"])
+     def test_decompose_propagates_bound_parameters(self, target_type, parameter_type):
+         """Verify bind-before-decompose preserves bound values."""

qiskit/circuit/parameterexpression.py

@@ -451,6 +451,17 @@ def log(self):
 
             return self._call(_log)
 
+    def sign(self):
+        """Sign of a ParameterExpression"""
+        if _optionals.HAS_SYMENGINE:
+            import symengine
+
+            return self._call(symengine.sign)
+        else:
+            from sympy import sign as _sign
+
+            return self._call(_sign)
+
     def __repr__(self):
         return f"{self.__class__.__name__}({str(self)})"
 

test/python/circuit/test_parameters.py

@@ -950,6 +950,15 @@ def test_rebinding_instruction_copy(self):
                 self.assertEqual(expected1, output1)
                 self.assertEqual(expected2, output2)
 
+    def test_sign_of_parameter(self):
+        """Test returning the sign of the value of the parameter"""
+
+        b = Parameter("phi")
+        sign_of_parameter = b.sign()
+        self.assertEqual(sign_of_parameter.assign(b, -3), -1)
+        self.assertEqual(sign_of_parameter.assign(b, 2), 1)
+        self.assertEqual(sign_of_parameter.assign(b, 0), 0)
+
     @combine(target_type=["gate", "instruction"], parameter_type=["numbers", "parameters"])
     def test_decompose_propagates_bound_parameters(self, target_type, parameter_type):
         """Verify bind-before-decompose preserves bound values."""