fixing bug in gatefunction evaluate

Signed-off-by: Alex McCaskey <mccaskeyaj@ornl.gov>

quantum/gate/ir/GateFunction.cpp

@@ -257,7 +257,8 @@ auto splitParameter = [](InstructionParameter instParam) {
   auto instParamStr = instParam.as<std::string>();
   split = xacc::split(instParamStr, ' ');
   for (auto s : split) {
-    if (!isNumber(s) && !s.empty()) {
+    xacc::trim(s);
+    if (!isNumber(s) && !s.empty() && s.find("pi") == std::string::npos) {
       rawParam = s;
     }
   }

quantum/gate/ir/tests/GateFunctionTester.cpp

@@ -22,7 +22,19 @@ const std::string expectedQasm = "H qreg1\n"
                                  "CNOT qreg1,qreg2\n"
                                  "CNOT qreg0,qreg1\n"
                                  "H qreg0\n";
+TEST(GateFunctionTester, checkComplexAngleExpression) {
+  GateFunction f("foo");
+  auto rx = std::make_shared<Rx>(std::vector<int>{0});
+  xacc::InstructionParameter p("-theta - pi/2");
+  rx->setParameter(0, p);
+  f.addInstruction(rx);
+  std::cout << f.toString() << "\n";
+
+  auto evaled = f({1.57});
 
+  std::cout << evaled->toString() << "\n";
+
+}
 TEST(GateFunctionTester, checkFunctionMethods) {
 
   GateFunction f("foo");