Actually, I have a question about this. I may have asked this before, so forgive me if I repeat.

Suppose my exact solution is sin(2*pi*x). I would like to compute the exact error against this function. Is this doable? I know you can resample it with a higher order function, but that is lame! Can't FFC treat it like a linear form and use quadrature to evaluate it? I know it isn't really a linear form, but FFC wouldn't know the difference! :) Maybe I am missing something...

- Shawn

On Wed, 10 Jun 2009, Martin Sandve Alnæs wrote:

The norm definitions should use "inner" instead of "dot" to handle
tensor fields as well.

Martin



On Wed, Jun 10, 2009 at 6:14 PM, Anders Logg<l...@simula.no> wrote:
On Wed, Jun 10, 2009 at 09:58:20AM -0500, Jehanzeb Hameed wrote:
Thanks. So I guess that means no such facility is available in C/C++ ?

No, since the computation depends on the space the functions are in
and so the code needs to be generated. In C++, you need to define a
form file for the norm. Look at

 site-packages/dolfin/norm.py

for how to define the norms.

--
Anders


On Wed, Jun 10, 2009 at 2:03 AM, Anders Logg<l...@simula.no> wrote:
On Tue, Jun 09, 2009 at 05:11:48PM -0500, Jehanzeb Hameed wrote:
Hello,

Is there a builtin function in dolfin to compute L^2 or H_1 norms? If
so, can you please point it out. If not, are there support functions
(e.g. a Gauss Quadrature table, computation of Jacobians, etc) which
can help in this?

Yes, this is available in the DOLFIN Python interface:

 norm(v)

The default computes the L^2 norm. Several options are available:

 L^2:     norm(v, 'L2')
 H^1:     norm(v, 'H1')      includes L^2 term
 H^1_0:   norm(v, 'H10')     does not include L^2 term
 H(div):  norm(v, 'Hdiv')    includes L^2 term
 H(div):  norm(v, 'Hdiv0')   does not include L^2 term
 H(curl): norm(v, 'Hcurl')   includes L^2 term
 H(curl): norm(v, 'Hcurl0')  does not include L^2 term


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