July 2025 - firedrake - imperial.ac.uk

Re: [firedrake] imposing boundary conditions for Hermite element MixedFunctionSpace
by Matthew Knepley 17 Jul '25

17 Jul '25

On Thu, Jul 17, 2025 at 11:06 AM Smail Merabet <merabetsmail(a)gmail.com> wrote: > The lower is a constant obstacle psi =-0.03 > I have the plot using freefem++ > 1. You cannot leave off the Cc if you want an answer from the Firedrake people 2. Did you plot your lower bound vector? The reason I ask is that I am absolutely sure that SNESVI will force the solution to be above the lower bound you input. Therefore I think you are inputting a lower bound different from what you expect. Thanks, Matt > On Thu, Jul 17, 2025 at 4:02 PM Matthew Knepley <knepley(a)gmail.com> wrote: > >> On Thu, Jul 17, 2025 at 10:49 AM Smail Merabet <merabetsmail(a)gmail.com> >> wrote: >> >>> Dear Matthew, >>> thanks for reply, I tried this: >>> >>> psi = Constant(-0.03) >>> >>> # Create the full function in mixed space >>> >>> obs = Function(Vh, name="Obstacle") >>> >>> upp = Function(Vh, name="Upper") >>> >>> >>> obs_sub1 = obs.sub(1) >>> >>> upp_sub1 = upp.sub(1) >>> >>> # Interpolate into the subfunctions >>> >>> obs_sub1.interpolate(conditional(lt(psi, 0), 0, psi)) >>> >> >> I do not understand the Firedrake side, but did you plot your lower >> bound? I have no idea what conditional gives back. >> >> Thanks, >> >> Matt >> >> >>> upp_sub1.interpolate(Constant(1e10)) >>> >>> But the result doesn't satisfy the constraint $w \geq \psi$ >>> >>> Many Thanks >>> >>> On Thu, Jul 17, 2025 at 1:22 PM Matthew Knepley <knepley(a)gmail.com> >>> wrote: >>> >>>> On Thu, Jul 17, 2025 at 7:52 AM Smail Merabet <merabetsmail(a)gmail.com> >>>> wrote: >>>> >>>>> Dear firedrake users, I try to solve a variational inequality using >>>>> snes-firedrake. >>>>> I have two unknown functions say (theta,w) >>>>> so the functionspace is Vh = MixedFunctionSpace([Th,Wh]) >>>>> where >>>>> Th = FunctionSpace(mesh, "Lagrange", 1) >>>>> Wh = FunctionSpace(mesh, "Lagrange", 2) >>>>> >>>>> >>>>> the inequality constraint concerns only $w$ >>>>> >>>>> I set : >>>>> obstacle = Function(Vh.sub(1)).interpolate((Constant(-0.03))) >>>>> upper = Function(Vh.sub(1)).interpolate(Constant(1e10)) >>>>> >>>> >>>> The SNES is operating on the full space, but you have interpolated >>>> constraints on the subspace. You have to inject those to full space vectors >>>> before setting the bounds. >>>> >>>> Thanks, >>>> >>>> Matt >>>> >>>> >>>>> *solver.solve(bounds=(obstacle, upper)) * >>>>> >>>>> but this line causes the following error: >>>>> >>>>> File "/Users/maths/Desktop/Firedrake/VI/Timoshenko-obs.py", line 64, >>>>> in <module> >>>>> solver.solve(bounds=(obstacle, upper)) >>>>> File "petsc4py/PETSc/Log.pyx", line 188, in >>>>> petsc4py.PETSc.Log.EventDecorator.decorator.wrapped_func >>>>> File "petsc4py/PETSc/Log.pyx", line 189, in >>>>> petsc4py.PETSc.Log.EventDecorator.decorator.wrapped_func >>>>> File >>>>> "/Users/maths/firedrake/src/firedrake/firedrake/adjoint_utils/variational_solver.py", >>>>> line 89, in wrapper >>>>> out = solve(self, **kwargs) >>>>> File >>>>> "/Users/maths/firedrake/src/firedrake/firedrake/variational_solver.py", >>>>> line 312, in solve >>>>> self.snes.setVariableBounds(lb, ub) >>>>> File "petsc4py/PETSc/SNES.pyx", line 1978, in >>>>> petsc4py.PETSc.SNES.setVariableBounds >>>>> petsc4py.PETSc.Error: error code 75 >>>>> [0] SNESVISetVariableBounds() at >>>>> /Users/maths/firedrake/src/petsc/src/snes/impls/vi/vi.c:424 >>>>> [0] SNESVISetVariableBounds_VI() at >>>>> /Users/maths/firedrake/src/petsc/src/snes/impls/vi/vi.c:443 >>>>> [0] Arguments are incompatible >>>>> [0] Incompatible vector lengths lower bound = 201 solution vector = >>>>> 302 >>>>> >>>>> >>>>> Hope that one can help me ... >>>>> >>>>> Best regards. >>>>> Smail. >>>>> >>>>> On Fri, Apr 11, 2025 at 9:11 AM Smail Merabet <merabetsmail(a)gmail.com> >>>>> wrote: >>>>> >>>>>> Dear firedrake users, >>>>>> >>>>>> I try to solve a fourth-order 1d nonlinear problem using the Hermite >>>>>> element in firedrake. >>>>>> The functional space for the weak solution is: >>>>>> $$\mathcal{H}\times \mathcal{H}/times H^{2}_{0} $$ >>>>>> where, >>>>>> $$ >>>>>> \mathcal{H} = \left\lbrace f\in H^2([0,\ell]), \; f(0)=0, \; f'(0)=0 >>>>>> \right\rbrace. >>>>>> $$ >>>>>> I can't impose the boundary conditions correctly. When I compile the >>>>>> code, I get the following error: >>>>>> FiniteElement('Hermite', interval, 3), name=None, index=1, >>>>>> component=None), IndexedProxyFunctionSpace(<firedrake.mesh.MeshTopology >>>>>> object at 0x125a2ce80>, FiniteElement('Hermite', interval, 3), name=None, >>>>>> index=2, component=None), name='None_None_None'), >>>>>> Mesh(VectorElement(FiniteElement('Lagrange', interval, 1), dim=1), 0)), 9) >>>>>> defined on incompatible FunctionSpace! >>>>>> >>>>>> Note the same problem was implemented using FEniCS with C0-interior >>>>>> penalty method, in the reference (sec. 3 eq 3.12-3.13): >>>>>> >>>>>> Enhanced models for the nonlinear bending of planar rods: >>>>>> localization phenomena and multistability >>>>>> by: >>>>>> Matteo Brunetti , Antonino Favata and Stefano Vidoli. >>>>>> >>>>>> I attached the codes to this email. >>>>>> >>>>>> Thanks in advance >>>>>> Smail MERABET >>>>>> >>>>>> _______________________________________________ >>>>> firedrake mailing list >>>>> firedrake(a)imperial.ac.uk >>>>> https://mailman.ic.ac.uk/mailman/listinfo/firedrake >>>>> >>>> >>>> >>>> -- >>>> What most experimenters take for granted before they begin their >>>> experiments is infinitely more interesting than any results to which their >>>> experiments lead. >>>> -- Norbert Wiener >>>> >>>> https://www.cse.buffalo.edu/~knepley/ >>>> <http://www.cse.buffalo.edu/~knepley/> >>>> >>> >> >> -- >> What most experimenters take for granted before they begin their >> experiments is infinitely more interesting than any results to which their >> experiments lead. >> -- Norbert Wiener >> >> https://www.cse.buffalo.edu/~knepley/ >> <http://www.cse.buffalo.edu/~knepley/> >> > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>

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Re: [firedrake] imposing boundary conditions for Hermite element MixedFunctionSpace
by Matthew Knepley 17 Jul '25

17 Jul '25

On Thu, Jul 17, 2025 at 10:49 AM Smail Merabet <merabetsmail(a)gmail.com> wrote: > Dear Matthew, > thanks for reply, I tried this: > > psi = Constant(-0.03) > > # Create the full function in mixed space > > obs = Function(Vh, name="Obstacle") > > upp = Function(Vh, name="Upper") > > > obs_sub1 = obs.sub(1) > > upp_sub1 = upp.sub(1) > > # Interpolate into the subfunctions > > obs_sub1.interpolate(conditional(lt(psi, 0), 0, psi)) > I do not understand the Firedrake side, but did you plot your lower bound? I have no idea what conditional gives back. Thanks, Matt > upp_sub1.interpolate(Constant(1e10)) > > But the result doesn't satisfy the constraint $w \geq \psi$ > > Many Thanks > > On Thu, Jul 17, 2025 at 1:22 PM Matthew Knepley <knepley(a)gmail.com> wrote: > >> On Thu, Jul 17, 2025 at 7:52 AM Smail Merabet <merabetsmail(a)gmail.com> >> wrote: >> >>> Dear firedrake users, I try to solve a variational inequality using >>> snes-firedrake. >>> I have two unknown functions say (theta,w) >>> so the functionspace is Vh = MixedFunctionSpace([Th,Wh]) >>> where >>> Th = FunctionSpace(mesh, "Lagrange", 1) >>> Wh = FunctionSpace(mesh, "Lagrange", 2) >>> >>> >>> the inequality constraint concerns only $w$ >>> >>> I set : >>> obstacle = Function(Vh.sub(1)).interpolate((Constant(-0.03))) >>> upper = Function(Vh.sub(1)).interpolate(Constant(1e10)) >>> >> >> The SNES is operating on the full space, but you have interpolated >> constraints on the subspace. You have to inject those to full space vectors >> before setting the bounds. >> >> Thanks, >> >> Matt >> >> >>> *solver.solve(bounds=(obstacle, upper)) * >>> >>> but this line causes the following error: >>> >>> File "/Users/maths/Desktop/Firedrake/VI/Timoshenko-obs.py", line 64, in >>> <module> >>> solver.solve(bounds=(obstacle, upper)) >>> File "petsc4py/PETSc/Log.pyx", line 188, in >>> petsc4py.PETSc.Log.EventDecorator.decorator.wrapped_func >>> File "petsc4py/PETSc/Log.pyx", line 189, in >>> petsc4py.PETSc.Log.EventDecorator.decorator.wrapped_func >>> File >>> "/Users/maths/firedrake/src/firedrake/firedrake/adjoint_utils/variational_solver.py", >>> line 89, in wrapper >>> out = solve(self, **kwargs) >>> File >>> "/Users/maths/firedrake/src/firedrake/firedrake/variational_solver.py", >>> line 312, in solve >>> self.snes.setVariableBounds(lb, ub) >>> File "petsc4py/PETSc/SNES.pyx", line 1978, in >>> petsc4py.PETSc.SNES.setVariableBounds >>> petsc4py.PETSc.Error: error code 75 >>> [0] SNESVISetVariableBounds() at >>> /Users/maths/firedrake/src/petsc/src/snes/impls/vi/vi.c:424 >>> [0] SNESVISetVariableBounds_VI() at >>> /Users/maths/firedrake/src/petsc/src/snes/impls/vi/vi.c:443 >>> [0] Arguments are incompatible >>> [0] Incompatible vector lengths lower bound = 201 solution vector = 302 >>> >>> >>> Hope that one can help me ... >>> >>> Best regards. >>> Smail. >>> >>> On Fri, Apr 11, 2025 at 9:11 AM Smail Merabet <merabetsmail(a)gmail.com> >>> wrote: >>> >>>> Dear firedrake users, >>>> >>>> I try to solve a fourth-order 1d nonlinear problem using the Hermite >>>> element in firedrake. >>>> The functional space for the weak solution is: >>>> $$\mathcal{H}\times \mathcal{H}/times H^{2}_{0} $$ >>>> where, >>>> $$ >>>> \mathcal{H} = \left\lbrace f\in H^2([0,\ell]), \; f(0)=0, \; f'(0)=0 >>>> \right\rbrace. >>>> $$ >>>> I can't impose the boundary conditions correctly. When I compile the >>>> code, I get the following error: >>>> FiniteElement('Hermite', interval, 3), name=None, index=1, >>>> component=None), IndexedProxyFunctionSpace(<firedrake.mesh.MeshTopology >>>> object at 0x125a2ce80>, FiniteElement('Hermite', interval, 3), name=None, >>>> index=2, component=None), name='None_None_None'), >>>> Mesh(VectorElement(FiniteElement('Lagrange', interval, 1), dim=1), 0)), 9) >>>> defined on incompatible FunctionSpace! >>>> >>>> Note the same problem was implemented using FEniCS with C0-interior >>>> penalty method, in the reference (sec. 3 eq 3.12-3.13): >>>> >>>> Enhanced models for the nonlinear bending of planar rods: localization >>>> phenomena and multistability >>>> by: >>>> Matteo Brunetti , Antonino Favata and Stefano Vidoli. >>>> >>>> I attached the codes to this email. >>>> >>>> Thanks in advance >>>> Smail MERABET >>>> >>>> _______________________________________________ >>> firedrake mailing list >>> firedrake(a)imperial.ac.uk >>> https://mailman.ic.ac.uk/mailman/listinfo/firedrake >>> >> >> >> -- >> What most experimenters take for granted before they begin their >> experiments is infinitely more interesting than any results to which their >> experiments lead. >> -- Norbert Wiener >> >> https://www.cse.buffalo.edu/~knepley/ >> <http://www.cse.buffalo.edu/~knepley/> >> > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>

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imposing boundary conditions for Hermite element MixedFunctionSpace
by Smail Merabet 17 Jul '25

17 Jul '25

Dear firedrake users, I try to solve a fourth-order 1d nonlinear problem using the Hermite element in firedrake. The functional space for the weak solution is: $$\mathcal{H}\times \mathcal{H}/times H^{2}_{0} $$ where, $$ \mathcal{H} = \left\lbrace f\in H^2([0,\ell]), \; f(0)=0, \; f'(0)=0 \right\rbrace. $$ I can't impose the boundary conditions correctly. When I compile the code, I get the following error: FiniteElement('Hermite', interval, 3), name=None, index=1, component=None), IndexedProxyFunctionSpace(<firedrake.mesh.MeshTopology object at 0x125a2ce80>, FiniteElement('Hermite', interval, 3), name=None, index=2, component=None), name='None_None_None'), Mesh(VectorElement(FiniteElement('Lagrange', interval, 1), dim=1), 0)), 9) defined on incompatible FunctionSpace! Note the same problem was implemented using FEniCS with C0-interior penalty method, in the reference (sec. 3 eq 3.12-3.13): Enhanced models for the nonlinear bending of planar rods: localization phenomena and multistability by: Matteo Brunetti , Antonino Favata and Stefano Vidoli. I attached the codes to this email. Thanks in advance Smail MERABET

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Solving Variational Inequality (vectorial case): pb self.snes.setVariableBounds(lb, ub)
by Smail Merabet 17 Jul '25

17 Jul '25

Dear firedrake users, I try to solve a variational inequality using snes-firedrake. I have two unknown functions say (theta,w) so the functionspace is Vh = MixedFunctionSpace([Th,Wh]) where Th = FunctionSpace(mesh, "Lagrange", 1) Wh = FunctionSpace(mesh, "Lagrange", 2) the inequality constraint concerns only $w$ I set : obstacle = Function(Vh.sub(1)).interpolate((Constant(-0.03))) upper = Function(Vh.sub(1)).interpolate(Constant(1e10)) *solver.solve(bounds=(obstacle, upper)) * but this line causes the following error: File "/Users/maths/Desktop/Firedrake/VI/Timoshenko-obs.py", line 64, in <module> solver.solve(bounds=(obstacle, upper)) File "petsc4py/PETSc/Log.pyx", line 188, in petsc4py.PETSc.Log.EventDecorator.decorator.wrapped_func File "petsc4py/PETSc/Log.pyx", line 189, in petsc4py.PETSc.Log.EventDecorator.decorator.wrapped_func File "/Users/maths/firedrake/src/firedrake/firedrake/adjoint_utils/variational_solver.py", line 89, in wrapper out = solve(self, **kwargs) File "/Users/maths/firedrake/src/firedrake/firedrake/variational_solver.py", line 312, in solve self.snes.setVariableBounds(lb, ub) File "petsc4py/PETSc/SNES.pyx", line 1978, in petsc4py.PETSc.SNES.setVariableBounds petsc4py.PETSc.Error: error code 75 [0] SNESVISetVariableBounds() at /Users/maths/firedrake/src/petsc/src/snes/impls/vi/vi.c:424 [0] SNESVISetVariableBounds_VI() at /Users/maths/firedrake/src/petsc/src/snes/impls/vi/vi.c:443 [0] Arguments are incompatible [0] Incompatible vector lengths lower bound = 201 solution vector = 302 Hope that one can help me ... Best regards. Smail.

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