I was just ready to send you a code when I realised what the problem was.

When I define Q as a scalar expression, updating it after every time
step does not update the expression in the weak form (I define a and L
outside the time loop and then just call the solver at every time step).
Defining the expression by

Q_expr = Expression("A*sin(2*pi*F*t)", t=t, A=A, F=F)
Q.interpolate(Q_expr)

and updating it by Q_expr.t = t works though.

Therefore I had to re-define the linear and bilinear parts of the weak
form inside the time loop for the first approach to work.


On 30/09/15 15:58, Lawrence Mitchell wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
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> On 30/09/15 15:51, Anna Kalogirou wrote:
>> Yes, I double - and triple - checked and I believe I am doing the
>> same thing in both approaches. I don't understand then why the
>> results are different.
> Hmph, can you show us some breaking code?
>
> Lawrence
>
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> =jk88

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--

  Dr Anna Kalogirou
  Research Fellow
  School of Mathematics
  University of Leeds

  http://www1.maths.leeds.ac.uk/~matak/


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