dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Mar 05, 2009 at 02:40:51PM -0500, Hatef Monajemi wrote:
> regardless of what operator you use ffc gives the following error:
> 
>  
> 
> "Dimensions don't match for scalar product."
> 
>  
> 
> try for example :
> 
>  
> 
> (v,w)= (v+v, w)
> 
> Is there a way to get around this?
> 
> Hatef

I checked and the problem is that v is a Python list with two elements

  v = [v[0], v[1]]

When you write v + v, the Python operator for addition of lists will
kick in and give a new Python list:

  v = [v[0], v[1], v[0], v[1]]

so the dimensions won't match when you take the inner product.

If you want to have v --> v + delta*grad(q), you can do something like

  v = [v[i] + delta*grad(q)[i] for i in len(v)]

This will be much better handled in upcoming versions of FFC which
will use the new form language UFL.

-- 
Anders

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