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[mspieg <mspieg@xxxxxxxxxxxxxxxxx>]

Hi all,
  is there a simple way to implement a known constant vector (e.g.  
the unit vector jhat = [ 0 1]') into a FFC form?

my specific  issue is that the right hand side of my PDE looks like

-\Div f\jhat = - df/dy

where f(x,y) is a user defined scalar function (and df/dy is not  
easily evaluated)

Given a test function v, the weak form (in pseudo-latex) is

\int dv/dy f dx - \int v f \jhat\dot ds

The question is how to evaluate the 2nd term in the FFC form language  
(the volume integral works fine as  v.dx(1)*f*dx)

ideally something like

jhat=??
L = v.dx(1)*f*dx) - v*f*jhat*ds

(or more generally for a known unit vector k  L=dot(grad(v),k)*f*dx -  
v*f*k*ds )

would be nice (in the same way as simple known constants can be built  
in directly)

But I'm flexible...all help greatly appreciated
marc


----------------------------------------------------
Marc Spiegelman
Lamont-Doherty Earth Observatory
Dept. of Applied Physics/Applied Math
Columbia University
http://www.ldeo.columbia.edu/~mspieg
tel: 845 704 2323 (SkypeIn)
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