UDPATE:

1. using standard `sin` and `cos` functions instead of inner functions

Author: Dark-CodeX

qubitverse/simulator/gates/gates.hh

@@ -59,7 +59,6 @@ namespace simulator
         static void apply_theta_gate(complex (&__s)[1 << n_qubits], const gate_type &__g_type, const double &__theta, const std::size_t &qubit_target);
         static void apply_2qubit_gate(complex (&__s)[1 << n_qubits], const gate_type &__g_type, const std::size_t &q_control, const std::size_t &q_target);
 
-      private:
         // a vector-space (hilbert-space) defined over complex numbers C
         // 1 << n_qubit translates to 2^N, where N is the number of qubit the hilbert-space(quantum-system) supports
         // memory consumption on x86_64 architecture for N-qubit system is: f(N) = 16 * 2^abs(N) bytes, that is exponential growth
@@ -127,17 +126,17 @@ namespace simulator
             break;
 
         case gate_type::ROTATION_X:
-            __g.matrix[0][0] = std::__complex_cos<double>(__theta / 2.0);
-            __g.matrix[0][1] = (complex){0.0, -1.0} * std::__complex_sin<double>(__theta / 2.0);
-            __g.matrix[1][0] = (complex){0.0, -1.0} * std::__complex_sin<double>(__theta / 2.0);
-            __g.matrix[1][1] = std::__complex_cos<double>(__theta / 2.0);
+            __g.matrix[0][0] = std::cos<double>(__theta / 2.0);
+            __g.matrix[0][1] = (complex){0.0, -1.0} * std::sin<double>(__theta / 2.0);
+            __g.matrix[1][0] = (complex){0.0, -1.0} * std::sin<double>(__theta / 2.0);
+            __g.matrix[1][1] = std::cos<double>(__theta / 2.0);
             break;
 
         case gate_type::ROTATION_Y:
-            __g.matrix[0][0] = std::__complex_cos<double>(__theta / 2.0);
-            __g.matrix[0][1] = -std::__complex_sin<double>(__theta / 2.0);
-            __g.matrix[1][0] = std::__complex_sin<double>(__theta / 2.0);
-            __g.matrix[1][1] = std::__complex_cos<double>(__theta / 2.0);
+            __g.matrix[0][0] = std::cos<double>(__theta / 2.0);
+            __g.matrix[0][1] = -std::sin<double>(__theta / 2.0);
+            __g.matrix[1][0] = std::sin<double>(__theta / 2.0);
+            __g.matrix[1][1] = std::cos<double>(__theta / 2.0);
             break;
 
         case gate_type::ROTATION_Z: