Add Python docs

cpp/dolfinx/fem/DirichletBC.h

@@ -473,21 +473,22 @@ class DirichletBC
  /// @brief Set entries in an array that are constrained by Dirichlet
  /// boundary conditions.
  ///
- /// Entries in the array `x` that are constrained by a Dirichlet
- /// boundary conditions are set to `alpha * (x_bc - x0)`, where `x_bc`
- /// is the boundary condition value.
+ /// Entries in `x` that are constrained by a Dirichlet boundary
+ /// conditions are set to `alpha * (x_bc - x0)`, where `x_bc` is the
+ /// (interpolated) boundary condition value.
  ///
  /// For elements with point-wise evaluated degrees-of-freedom, e.g.
- /// Lagrange element, `x_bc` is the value of the boundary condition at
- /// the degree-of-freedom. For elements with moment
+ /// Lagrange elements, `x_bc` is the value of the boundary condition
+ /// at the degree-of-freedom. For elements with moment
  /// degrees-of-freedom, `x_bc` is the value of the boundary condition
  /// interpolated into the finite element space.
  ///
  /// If `x` includes ghosted entries (entries available on the calling
  /// rank but owned by another rank), ghosted entries constrained by a
  /// Dirichlet condition will also be set.
  ///
- /// @param[in,out] x The array to modify.
+ /// @param[in,out] x Array to modify for Dirichlet boundary
+ /// conditions.
  /// @param[in] x0 Optional array used in computing the value to set.
  /// If not provided it is treated as zero.
  /// @param[in] alpha Scaling to apply.

python/dolfinx/fem/bcs.py

@@ -133,20 +133,31 @@ def function_space(self) -> dolfinx.fem.FunctionSpace:
  return self._cpp_object.function_space
 
  def set(
- self, b: npt.NDArray, x0: typing.Optional[npt.NDArray[np.int32]] = None, alpha: float = 1
+ self, x: npt.NDArray, x0: typing.Optional[npt.NDArray[np.int32]] = None, alpha: float = 1
  ) -> None:
- """Insert boundary condition values into vector.
+ """Set entries in an array that are constrained by Dirichlet boundary conditions.
 
- Only local (owned) entries are set, hence communication after
- calling this function is not required unless ghost entries need to
- be updated to the boundary condition value.
+ Entries in an array ``x`` that are constrained by a Dirichlet
+ boundary conditions are set to ``alpha * (x_bc - x0)``, where
+ ``x_bc`` is the (interpolated) boundary condition value.
+
+ For elements with point-wise evaluated degrees-of-freedom, e.g.
+ Lagrange elements, ``x_bc`` is the value of the boundary condition
+ at the degree-of-freedom. For elements with moment
+ degrees-of-freedom, ``x_bc`` is the value of the boundary condition
+ interpolated into the finite element space.
+
+ If `x` includes ghosted entries (entries available on the calling
+ rank but owned by another rank), ghosted entries constrained by a
+ Dirichlet condition will also be set.
 
  Args:
- b:
- x0:
- alpha:
+ x: Array to modify for Dirichlet boundary conditions.
+ x0: Optional array used in computing the value to set. If
+ not provided it is treated as zero.
+ alpha: Scaling factor.
  """
- self._cpp_object.set(b, x0, alpha)
+ self._cpp_object.set(x, x0, alpha)
 
  def dof_indices(self) -> tuple[npt.NDArray[np.int32], int]:
  """Access dof indices `(local indices, unrolled)`, including ghosts, to