Function¶
-
class
dolfin.functions.function.
Function
(*args, **kwargs)¶ Bases:
ufl.coefficient.Coefficient
,dolfin.cpp.function.Function
This class represents a function \(u_h\) in a finite element function space \(V_h\), given by
\[u_h = \sum_{i=1}^n U_i \phi_i,\]where \(\{\phi_i\}_{i=1}^n\) is a basis for \(V_h\), and \(U\) is a vector of expansion coefficients for \(u_h\).
- Arguments
There is a maximum of three arguments. The first argument must be a Function or a
FunctionSpace
.If instantiated from another Function, the (optional) second argument must be an integer denoting the number of sub functions to extract.
In addition can a name argument be passed overruling the default name
- Examples
Create a Function:
from a
FunctionSpace
V
f = Function(V)
from another Function
f
g = Function(f)
from a
FunctionSpace
V
and aGenericVector
v
g = Function(V, v)
from a
FunctionSpace
and a filename containg aGenericVector
g = Function(V, 'MyVectorValues.xml')
Initialize Function.
-
assign
(rhs)¶ Assign either a Function or linear combination of Functions.
- Arguments
- rhs (_Function_)
- A Function or a linear combination of Functions. If a linear combination is passed all Functions need to be in the same FunctionSpaces.
-
split
(deepcopy=False)¶ Extract any sub functions.
A sub function can be extracted from a discrete function that is in a
MixedFunctionSpace
or in aVectorFunctionSpace
. The sub function resides in the subspace of the mixed space.- Arguments
- deepcopy
- Copy sub function vector instead of sharing
-
str
(verbose=False)¶ Return an informative str representation of itself
-
sub
(i, deepcopy=False)¶ Return a sub function.
The sub functions are numbered from i = 0..N-1, where N is the total number of sub spaces.
- Arguments
- i : int
- The number of the sub function
-
ufl_element
()¶ Return ufl element
-
ufl_evaluate
(x, component, derivatives)¶ Function used by ufl to evaluate the Function