Simulating Two Qubits - C Code

// CNOT, swap q[2] and q[3]
//
// Python: self.onezero, self.oneone = self.oneone, self.onezero
//
void CNOT( double complex q[4])
{
  double complex t = q[3];  q[3] = q[2];  q[2] = t;
}

// Z gate on first qubit
//
// Python: self.onezero *= -1;  self.oneone  *= -1
//
void Z( double complex q[4])
{
  q[2] = -q[2];  q[3] = -q[3];
}