def assign(self, expr, subset=None):
"""Set the :class:`Function` value to the pointwise value of
expr. expr may only contain :class:`Function`\s on the same
:class:`.FunctionSpace` as the :class:`Function` being assigned to.
Similar functionality is available for the augmented assignment
operators `+=`, `-=`, `*=` and `/=`. For example, if `f` and `g` are
both Functions on the same :class:`FunctionSpace` then::
f += 2 * g
will add twice `g` to `f`.
If present, subset must be an :class:`pyop2.Subset` of
:attr:`node_set`. The expression will then only be assigned
to the nodes on that subset.
"""
if isinstance(expr, Function) and \
expr._function_space == self._function_space:
expr.dat.copy(self.dat, subset=subset)
return self
assemble_expressions.evaluate_expression(
assemble_expressions.Assign(self, expr), subset)
return self
def __idiv__(self, expr):
if np.isscalar(expr):
self.dat /= expr
return self
if isinstance(expr, Function) and \
expr._function_space == self._function_space:
self.dat /= expr.dat
return self
assemble_expressions.evaluate_expression(
assemble_expressions.IDiv(self, expr))
return self