qiskit/providers/basicaer/qasm_simulator.py
def _add_qasm_measure(self, qubit, cmembit, cregbit=None):
        """Apply a measure instruction to a qubit.

        Args:
            qubit (int): qubit is the qubit measured.
            cmembit (int): is the classical memory bit to store outcome in.
            cregbit (int, optional): is the classical register bit to store outcome in.
        """
        # get measure outcome
        outcome, probability = self._get_measure_outcome(qubit)
        # update classical state
        membit = 1 << cmembit
        self._classical_memory = (self._classical_memory & (~membit)) | (int(outcome) << cmembit)

        if cregbit is not None:
            regbit = 1 << cregbit
            self._classical_register = \
                (self._classical_register & (~regbit)) | (int(outcome) << cregbit)

        # update quantum state
        if outcome == '0':
            update_diag = [[1 / np.sqrt(probability), 0], [0, 0]]
        else:
            update_diag = [[0, 0], [0, 1 / np.sqrt(probability)]]
        # update classical state
        self._add_unitary_single(update_diag, qubit)
def _add_qasm_measure(self, qubit, cmembit, cregbit=None):
        """Apply a measure instruction to a qubit.

        Args:
            qubit (int): qubit is the qubit measured.
            cmembit (int): is the classical memory bit to store outcome in.
            cregbit (int, optional): is the classical register bit to store outcome in.
        """
        # get measure outcome
        outcome, probability = self._get_measure_outcome(qubit)
        # update classical state
        membit = 1 << cmembit
        self._classical_memory = (self._classical_memory & (~membit)) | (int(outcome) << cmembit)

        if cregbit is not None:
            regbit = 1 << cregbit
            self._classical_register = \
                (self._classical_register & (~regbit)) | (int(outcome) << cregbit)

        # update quantum state
        if outcome == '0':
            update_diag = [[1 / np.sqrt(probability), 0], [0, 0]]
        else:
            update_diag = [[0, 0], [0, 1 / np.sqrt(probability)]]
        # update classical state
        self._add_unitary_single(update_diag, qubit)
Apply a measure instruction to a qubit.

        Args:
            qubit (int): qubit is the qubit measured.
            cmembit (int): is the classical memory bit to store outcome in.
            cregbit (int, optional): is the classical register bit to store outcome in.