ufl team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Kristian Oelgaard wrote:
> 
> 
> On 3 February 2010 09:48, Garth Wells <gnw20@xxxxxxxxx> wrote:
>> Bug was in FFC, marking as invalid.
>>
>> ** Changed in: ufl
>>       Status: Confirmed => Invalid
> 
> I would call this a bug in UFL.
> 
> from ufl.algorithms import propagate_restrictions
> cell = triangle
> V = FiniteElement("DG", cell, 1)
> u = Coefficient(V)
> flux2 = variable(grad(u))
> 
> e = avg(flux2)
> print e
> print propagate_restrictions(e)
> 
> produces:
> 
> { A | A_{i_8} = 0.5 * ((((var0(grad(w_0)))('-')) +
> ((var0(grad(w_0)))('+')))[i_8]) }
> { A | A_{i_8} = 0.5 * (({ A | A_{i_9} = 2 *
> ((var0(grad((w_0)('-'))))[i_9]) })[i_8]) }
> 
> I don't see why UFL shouldn't be able to handle that.
> 

Reply to the bug report so we can track the discussion.

Garth

> Kristian
> 
>> -- 
>> variable + facet restriction broken
>> https://bugs.launchpad.net/bugs/512425
>> You received this bug notification because you are a member of UFL Core
>> Team, which is the registrant for UFL.
>>
>> Status in Unified Form Language: Invalid
>>
>> Bug description:
>> UFL is doing something wrong when a Function which is made into a
>> 'variable', e.g.  u = variable(u), is used for a facet integral. The
>> below code demonstrates the error.
>>
>>
>>
>> from dolfin import *
>> from numpy import random
>>
>> mesh = UnitSquare(24, 24)
>> n = FacetNormal(mesh)
>> V = FunctionSpace(mesh, "DG", 1)
>> v = TestFunction(V)
>> u = Function(V)
>>
>> # Fill vector with some numbers
>> random.seed(2)
>> u.vector().set_local( random.rand(u.vector().size()) )
>>
>> # Define flux. One without, and one with 'variable'
>> flux1 = grad(u)
>> flux2 = variable(grad(u))
>>
>> # Define linear forms
>> L0 = dot(jump(v, n), avg(grad(u)))*dS
>> L1 = dot(jump(v, n), avg(flux1))*dS
>> L2 = dot(jump(v, n), avg(flux2))*dS
>> L3 = dot(jump(v, n), flux2('+'))*dS
>> L4 = dot(jump(v, n), flux2('-'))*dS
>>
>> print "Testing matrix norms. All should be equal."
>> print "Norm case 0:                  ", assemble(L0).norm("l2")
>> print "Norm case 1:                  ", assemble(L1).norm("l2")
>> print "Norm case 2 (using variable): ", assemble(L2).norm("l2")
>> print "Norm case 3 (using variable): ", assemble(L3).norm("l2")
>> print "Norm case 4 (using variable): ", assemble(L4).norm("l2")
>>
>>
>>
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> Mailing list: https://launchpad.net/~ffc
> Post to     : ffc@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~ffc
> More help   : https://help.launchpad.net/ListHelp