I understand your point. However, I just checked in some updates of
NewFunction that lets a user do
class MyFunction : NewFunctionExpression
{
real operator()(const Point& p)
{
return sin(p.x);
}
};
MyFunction f;
Could you take a look and see if you like the new/old solution?
It's not very complicated. The projection just checks if data is null
and in that case calls the user defined evaluation operator.
/Anders
On Mon, Feb 14, 2005 at 03:35:25PM +0100, Johan Jansson wrote:
I'm thinking about how to enable user-defined functions, but I don't
have a clear solution.
The idea right now seems to be to subclass NewFunction, a la:
// Source term
// Example using NewFunction
class F : public NewFunction
{
public:
F(const Mesh& mesh, const NewFiniteElement& element, NewVector& x) :
NewFunction(mesh, element, x)
{
}
virtual real operator()(const Point& p)
{
real pi = DOLFIN_PI;
return 14.0 * pi*pi * sin(pi*p.x) * sin(2.0*pi*p.y) * sin(3.0*pi*p.z);
}
};
We could have a separate constructor when an expression is given, and
then project the given expression.
I think this is a bit ugly though, it seems unnecessarily complex.
Another solution would be to separate the expression out into a
functor (function class), and the example would be:
class F : Expression
{
virtual real operator()(const Point& p)
{
real pi = DOLFIN_PI;
return 14.0 * pi*pi * sin(pi*p.x) * sin(2.0*pi*p.y) * sin(3.0*pi*p.z);
}
}
then:
int main()
{
...
F fexpression;
NewFunction f(mesh, element, fexpression);
..
}
This seems much more natural. When we have a function given by the
values of its degrees of freedom, we pass a vector with the dofs to
NewFunction. When we have a function given by an expression, we pass
the expression to NewFunction and it projects it and stores it as
values of the dofs. However, we would need to introduce a new class:
Expression. What do you think?
Johan
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