Expression¶
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class
dolfin.cpp.function.
Expression
(*args)¶ Bases:
dolfin.cpp.function.GenericFunction
This class represents a user-defined expression. Expressions can be used as coefficients in variational forms or interpolated into finite element spaces. An expression is defined by overloading the
eval
method. Users may choose to overload either a simple version ofeval
, in the case of expressions only depending on the coordinate x, or an optional version for expressions depending on x and mesh data like cell indices or facet normals. The geometric dimension (the size of x) and the value rank and dimensions of an expression must supplied as arguments to the constructor.Copy constructor
Parameters: Expression & expression (const) – ( Expression
) Object to be copied.-
eval
()¶ Evaluate at given point (deprecated)
Parameters: - double > & values (Array<) – (Array<double>) The values at the point.
- Array< double > & x (const) – (Array<double>) The coordinates of the point.
Return type: void
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eval_cell
()¶ Evaluate at given point in given cell (deprecated)
Parameters: - double > & values (Array<) – (Array<double>) The values at the point.
- Array< double > & x (const) – (Array<double>) The coordinates of the point.
- ufc::cell & cell (const) – (ufc::cell) The cell which contains the given point.
Return type: void
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get_generic_function
()¶ Property getter for type “GenericFunction” Used in pybind11 Python interface to get the value of a python attribute
Parameters: name (std::string) – Return type: std::shared_ptr< dolfin::GenericFunction >
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get_property
()¶ Property getter for type “double” Used in pybind11 Python interface to get the value of a python attribute
Parameters: name (std::string) – Return type: double
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set_generic_function
()¶ Property setter for type “GenericFunction” Used in pybind11 Python interface to attach a value to a python attribute
Parameters: - name (std::string) –
- GenericFunction > f (std::shared_ptr<) –
Return type: void
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set_property
()¶ Property setter for type “double” Used in pybind11 Python interface to attach a value to a python attribute
Parameters: - name (std::string) –
- value (double) –
Return type: void
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thisown
¶ The membership flag
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value_shape
()¶ Return value shape
Return type: std::vector< std::size_t > Returns: std::vector<std::size_t> The value shape.
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