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On Wed, Jun 10, 2009 at 01:28:20PM -0400, Shawn Walker wrote: > Is errornorm also a c++ function? or is this only Python? It's also just Python. -- Anders > - Shawn > > On Wed, 10 Jun 2009, Anders Logg wrote: > >> On Wed, Jun 10, 2009 at 06:46:53PM +0200, Martin Sandve Alnæs wrote: >>> Not a linear form, but a functional. That's what norm does anyway. >>> >>> u = Function(element) >>> x, y, z = tetrahedron.x >>> L2 = (sin(2*pi*x) - u)**2*dx >>> >>> You still have to make sure you compile >>> with sufficient quadrature order though. >> >> That may not be numerically stable depending on how the form compiler >> expands the expression into terms. Use the function errornorm() which >> works around this and automatically computes the norm: >> >> e = errornorm(u, u_h) >> >> Look at the documentation in errornorm.py for a longer explanation. >> >> >> >> >>> >>> On Wed, Jun 10, 2009 at 6:33 PM, Shawn Walker<walker@xxxxxxxxxxxxxxx> wrote: >>>> 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<logg@xxxxxxxxx> 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. >>>>>> >>>>>> >>>>>> >>>>>>> On Wed, Jun 10, 2009 at 2:03 AM, Anders Logg<logg@xxxxxxxxx> 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 >>>>>>>> >>>>>>>> >>>>>>>> -----BEGIN PGP SIGNATURE----- >>>>>>>> Version: GnuPG v1.4.9 (GNU/Linux) >>>>>>>> >>>>>>>> iEYEARECAAYFAkovWqUACgkQTuwUCDsYZdGb3gCfa2gWnzealWzkjPoRj8hf3cr/ >>>>>>>> 0EUAoJh4mpaIzRU9eCnnC+XWlupu6SV0 >>>>>>>> =so4c >>>>>>>> -----END PGP SIGNATURE----- >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> DOLFIN-dev mailing list >>>>>>>> DOLFIN-dev@xxxxxxxxxx >>>>>>>> http://www.fenics.org/mailman/listinfo/dolfin-dev >>>>>>>> >>>>>>>> >>>>>>> _______________________________________________ >>>>>>> DOLFIN-dev mailing list >>>>>>> DOLFIN-dev@xxxxxxxxxx >>>>>>> http://www.fenics.org/mailman/listinfo/dolfin-dev >>>>>> >>>>>> -----BEGIN PGP SIGNATURE----- >>>>>> Version: GnuPG v1.4.9 (GNU/Linux) >>>>>> >>>>>> iEYEARECAAYFAkov28sACgkQTuwUCDsYZdE8KQCdEI7wS27QaNw9knI2U9L+RVST >>>>>> xeUAnRdLrrhAVzsBn6nO1b6CLEpF64ey >>>>>> =a7iu >>>>>> -----END PGP SIGNATURE----- >>>>>> >>>>>> _______________________________________________ >>>>>> DOLFIN-dev mailing list >>>>>> DOLFIN-dev@xxxxxxxxxx >>>>>> http://www.fenics.org/mailman/listinfo/dolfin-dev >>>>>> >>>>>> >>>>> _______________________________________________ >>>>> DOLFIN-dev mailing list >>>>> DOLFIN-dev@xxxxxxxxxx >>>>> http://www.fenics.org/mailman/listinfo/dolfin-dev >>>>> >>>> >>> _______________________________________________ >>> DOLFIN-dev mailing list >>> DOLFIN-dev@xxxxxxxxxx >>> http://www.fenics.org/mailman/listinfo/dolfin-dev >>
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