Update InitializeGate with latest sympy changes

qiskit/_instruction.py

@@ -40,8 +40,9 @@ class Instruction(object):
         self.name = name
         self.param = []
         for p in param:
-            if not isinstance(p, Basic):
-                # if item in param not symbolic, make it symbolic
+            if not isinstance(p, (Basic, complex)):
+                # If the item in param is not symbolic and not complex (used
+                # by InitializeGate), make it symbolic.
                 self.param.append(Number(p))
             else:
                 self.param.append(p)

qiskit/extensions/quantum_initializer/_initializer.py

@@ -14,7 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 # =============================================================================
-
 """
 Initialize qubit registers to desired arbitrary state.
 """
@@ -36,7 +35,7 @@ _EPS = 1e-10  # global variable used to chop very small numbers to zero
 
 
 class InitializeGate(CompositeGate):
-    """ Complex amplitude initialization.
+    """Complex amplitude initialization.
 
     Class that implements the (complex amplitude) initialization of some
     flexible collection of qubit registers (assuming the qubits are in the
@@ -173,6 +172,9 @@ class InitializeGate(CompositeGate):
         qubit from the zero vector.
         """
         [a_complex, b_complex] = pair_of_complex
+        # Force a and b to be complex, as otherwise numpy.angle might fail.
+        a_complex = complex(a_complex)
+        b_complex = complex(b_complex)
         mag_a = numpy.absolute(a_complex)
         final_r = float(numpy.sqrt(mag_a ** 2 + numpy.absolute(b_complex) ** 2))
         if final_r < _EPS: