_______________________________________ Fra: [email protected] [[email protected]] på vegne af Johannes Ring [[email protected]] Sendt: 5. november 2014 11:21 Til: Benjamin Kehlet Cc: Henrik Garde; [email protected] Emne: Re: [FEniCS-support] dolfin from PPA is not compiled with CGAL
On Wed, Nov 5, 2014 at 11:08 AM, Benjamin Kehlet <[email protected]> wrote: > 2014-11-05 9:47 GMT+01:00 Johannes Ring <[email protected]>: >> On Tue, Nov 4, 2014 at 6:33 PM, Henrik Garde <[email protected]> wrote: >>> The newest version of Dolfin 1.4 in the fenics PPA for Ubuntu 14.04 does >>> not seem to be compiled with CGAL (worked fine before an update today). >> >> Yes, CGAL support was disabled in favor of mshr: >> >> https://bitbucket.org/benjamik/mshr/wiki/Home >> >>>> has_cgal() >>> False >>> >>> This prevents for instance the use of CircleMesh, and gives the error: >>> >>> Traceback (most recent call last): >>> File "<stdin>", line 1, in <module> >>> File "/usr/lib/python2.7/dist-packages/dolfin/cpp/mesh.py", line 8006, in >>> __init__ >>> _mesh.CircleMesh_swiginit(self,_mesh.new_CircleMesh(*args)) >>> RuntimeError: >> >> With mshr you can create a circle mesh for instance like this: >> >> import dolfin >> from mshr import * >> mesh = generate_mesh(Circle(dolfin.Point(0, 0), 1), 32) >> dolfin.plot(mesh, interactive=True) >> This code definitely generates a mesh, thank you. However the boundary of the circle seems to be poorly approximated, at first glance (even for a very fine mesh) the boundary looks like a 32-sided polygon, and integration along the boundary also confirms this: mesh = generate_mesh(Circle(Point(0, 0), 1), 200) V = FunctionSpace(mesh,'CG',1) print abs(2*pi - assemble(interpolate(Constant(1.0),V)*ds)) returns 0.0100883260877 This discrepancy does not decrease with a higher number N in the generate_mesh(... , N). I do not recall the old CircleMesh having this problem, and it seems problematic in terms of solving boundary value problems. >> @Benjamin: Will CircleMesh be available in mshr to make it more >> backwards compatible with older DOLFIN? > > Not currently, but it would be easy to add. I guess there was a > SphereMesh in Dolfin as well? Anything else? Yes, in addition to CircleMesh and SphereMesh, it was also at least EllipseMesh and EllipsoidMesh. Johannes > Benjamin > >> >> Johannes >> >>> *** >>> ------------------------------------------------------------------------- >>> *** DOLFIN encountered an error. If you are not able to resolve this issue >>> *** using the information listed below, you can ask for help at >>> *** >>> *** [email protected] >>> *** >>> *** Remember to include the error message listed below and, if possible, >>> *** include a *minimal* running example to reproduce the error. >>> *** >>> *** >>> ------------------------------------------------------------------------- >>> *** Error: Unable to generate ellipse mesh. >>> *** Reason: Generation of ellipse meshes requires DOLFIN to be configured >>> with CGAL. >>> *** Where: This error was encountered inside EllipseMesh.cpp. >>> *** Process: unknown >>> *** >>> *** DOLFIN version: 1.4.0 >>> *** Git changeset: unknown >>> *** >>> ------------------------------------------------------------------------- >>> _______________________________________________ >>> fenics-support mailing list >>> [email protected] >>> http://fenicsproject.org/mailman/listinfo/fenics-support _______________________________________________ fenics-support mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics-support
