Improve the docs for QubitCircuit.add_gate (#180)

src/qutip_qip/circuit/circuit.py

@@ -203,22 +203,24 @@ def add_gate(
         gate: string or :class:`~.operations.Gate`
             Gate name. If gate is an instance of :class:`~.operations.Gate`,
             parameters are unpacked and added.
-        targets: list
-            Gate targets.
-        controls: list
-            Gate controls.
-        arg_value: float
-            Argument value(phi).
-        arg_label: string
+        targets: int or list, optional
+            Index for the target qubits.
+        controls: int or list, optional
+            Indices for the (quantum) control qubits.
+        arg_value: Any, optional
+            Arguments for the gate. It will be used when generating the
+            unitary matrix. For predefined gates, they are used when
+            calling the ``get_compact_qobj`` methods of a gate.
+        arg_label: string, optional
             Label for gate representation.
-        index : list
+        index : list, optional
             Positions to add the gate. Each index in the supplied list refers
             to a position in the original list of gates.
         classical_controls : int or list of int, optional
-            indices of classical bits to control gate on.
+            Indices of classical bits to control the gate.
         control_value : int, optional
-            value of classical bits to control on, the classical controls are
-            interpreted as an integer with lowest bit being the first one.
+            Value of classical bits to control on, the classical controls are
+            interpreted as an integer with the lowest bit being the first one.
             If not specified, then the value is interpreted to be
             2 ** len(classical_controls) - 1
             (i.e. all classical controls are 1).

src/qutip_qip/compiler/scheduler.py

@@ -358,10 +358,10 @@ def schedule(
         repeat_num=0,
     ):
         """
-        Schedule a `QubitCircuit`,
-        a list of `Gates` or a list of `Instruction`.
-        For pulse schedule, the execution time for each `Instruction`
-        is given in its `duration` attributes.
+        Schedule a :obj:`.QubitCircuit`,
+        a list of :obj:`.Gates` or a list of :obj:`.Instruction`.
+        For pulse schedule, the execution time for each :obj:`.Instruction`
+        is given in its ``duration`` attributes.
 
         The scheduler first generates a quantum gates dependency graph,
         containing information about
@@ -398,18 +398,18 @@ def schedule(
             each with an attribute `duration`
             that indicates the execution time of this instruction.
         gates_schedule: bool, optional
-            `True`, if only gates schedule is needed.
+            ``True``, if only gates schedule is needed.
             This saves some computation
             that is only useful to pulse schedule.
-            If the input `circuit` is a `QubitCircuit`,
-            it will be assigned to `True` automatically.
+            If the input ``circuit`` is a :obj:`.QubitCircuit`,
+            it will be assigned to ``True`` automatically.
             Otherwise, the default is `False`.
         return_cycles_list: bool, optional
-            If `True`, the method returns the `cycles_list`,
-            e.g. [{0, 2}, {1, 3}],
+            If ``True``, the method returns the ``cycles_list``,
+            e.g. ``[{0, 2}, {1, 3}]``,
             which means that the first cycle contains gates0 and gates2
             while the second cycle contains gates1 and gates3.
-            It is only usefull for gates schedule.
+            It is only useful for gates schedule.
         random_shuffle: bool, optional
             If the commuting gates are randomly scuffled to explore
             larger search space.