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[Martin Sandve Alnæs <martinal@xxxxxxxxx>]

Hi Patrick,
w**2 doesn't work because w is a vector valued expression.
This should have been detected already at w**2, I'll take a look at that.
Instead, try:
  f = inner(w, w)/2*dx

Setting
  L, a = F, J
should work fine, or you can do
  forms = [F, J]
at the end of the form file (then you can define as many forms as you
like in one file).

Martin



On Sat, Jun 6, 2009 at 7:05 PM, Patrick Riesen<priesen@xxxxxxxxxxxxxxx> wrote:
> hello
>
> following the example in the ufl manual it's possible to do things like
> element = VectorElement("CG", cell, 3)
> w = Function(element)
> f = w**2/2*dx
> F = derivative(f, w)
> J = derivative(F, w)
>
> but how do i give e.g. F and/or J to the forms a and L to get the code?
> when i tried just e.g. a = F it get
>
> ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
> f = [[ v_{-1}[4], v_{-1}[5] ]]
> g = 2
> ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
> Expecting scalar expression f in f**g.
> *** Expecting scalar expression f in f**g.
>
>
> thanks for the help,
> patrick
>
> Anders Logg wrote:
>> Yes, the bilinear form should be the linearized nonlinear form (not
>> minus).
>>
>> Note that with UFL, it's now possible to just write down the nonlinear
>> form
>>
>>   (v, F(u)) = 0 for all v
>>
>> and then let UFL compute the linearization.
>>
>>
>
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