June 2019 - firedrake - imperial.ac.uk

Interpolate DG functions between meshes
by Sentz, Peter 05 Jun '19

05 Jun '19

For functions in CG spaces, I usually do the following to interpolate between meshes: meshc = UnitSquareMesh(2,2) mesh = UnitSquareMesh(4,4) Vc = FunctionSpace(meshc,'CG',1) V = FunctionSpace(mesh,'CG',1) xc,yc = SpatialCoordinate(meshc) fc = 1 + xc + yc Fc = Function(Vc).interpolate(fc) W = VectorFunctionSpace(mesh,'CG',1) X = interpolate(mesh.coordinates,W).dat.data_ro Fc_I = Function(V) Fc_I.dat.data[:] = Fc.at(X) I interpolate the mesh coordinates to the second mesh and use the .at() routine to evaluate the function defined on the coarse mesh on those points. It agrees with directly interpolating the expression onto the second mesh (within machine precision). However, if I am using 'DG' function spaces, the .at() routine is single valued, so if I apply this method to a function Fc that has multiple values at a node, it will force all values at the same mesh node to be identical. How would you suggest interpolating DG functions between meshes? Thanks, Peter

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complex problem with sphere meshes
by Shipton, Jemma 04 Jun '19

04 Jun '19

Hi All, The following used to work on the complex branch but now throws an error.... mesh=IcosahedralSphereMesh(1, 3) x=SpatialCoordinate(mesh) mesh.init_cell_orientations(x) The error is: File "/Users/jshipton/complex-firedrake/src/firedrake/firedrake/mesh.py", line 1216, in init_cell_orientations f.interpolate(ufl.dot(expr, ufl.cross(ReferenceGrad(x)[:, 0], ReferenceGrad(x)[:, 1]))) File "/Users/jshipton/complex-firedrake/src/firedrake/firedrake/function.py", line 334, in interpolate return interpolation.interpolate(expression, self, subset=subset) File "/Users/jshipton/complex-firedrake/src/firedrake/firedrake/interpolation.py", line 37, in interpolate return Interpolator(expr, V, subset=subset).interpolate() File "/Users/jshipton/complex-firedrake/src/firedrake/firedrake/interpolation.py", line 57, in __init__ self.callable = make_interpolator(expr, V, subset) File "/Users/jshipton/complex-firedrake/src/firedrake/firedrake/interpolation.py", line 112, in make_interpolator loops.extend(_interpolator(V, f.dat, expr, subset)) File "/Users/jshipton/complex-firedrake/src/firedrake/firedrake/interpolation.py", line 171, in _interpolator ast, oriented, needs_cell_sizes, coefficients = compile_ufl_kernel(expr, to_pts, coords, parameters=parameters) ValueError: too many values to unpack (expected 4) Any help would be appreciated! Thanks! Jemma

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using AuxiliaryOperatorPC in MG
by Cotter, Colin J 03 Jun '19

03 Jun '19

Hi folks, The following set of options: ap_mg_params = {"mat_type": "matfree", "snes_type": "ksponly", "ksp_type": "gmres", "ksp_rtol": 1.0e-8, "ksp_atol": 0.0, "ksp_max_it": 1000, "ksp_monitor": None, "ksp_converged_reason": None, "ksp_norm_type": "unpreconditioned", "pc_type": "mg", "mg_coarse_ksp_type": "preonly", "mg_coarse_pc_type": "python", "mg_coarse_pc_python_type": "firedrake.AssembledPC", "mg_coarse_assembled_pc_type": "lu", "mg_coarse_assembled_pc_factor_mat_solver_type": "mumps", "mg_levels_ksp_type": "richardson", "mg_levels_ksp_max_it": 1, "mg_levels_ksp_richardson_scale": 1/3, "mg_levels_pc_type": "python", "mg_levels_pc_python_type": "__main__.Shifted", "mg_levels_aux_pc_type": "python", "mg_levels_aux_pc_python_type": "firedrake.PatchPC", "mg_levels_aux_patch_pc_patch_save_operators": True, "mg_levels_aux_patch_pc_patch_partition_of_unity": False, "mg_levels_aux_patch_pc_patch_sub_mat_type": "seqaij", "mg_levels_aux_patch_pc_patch_construct_type": "star", "mg_levels_aux_patch_pc_patch_multiplicative": False, "mg_levels_aux_patch_pc_patch_symmetrise_sweep": False, "mg_levels_aux_patch_pc_patch_construct_dim": 0, "mg_levels_aux_patch_sub_ksp_type": "preonly", "mg_levels_aux_patch_sub_pc_type": "lu"} causes the message at the bottom of this email (below which is my Shifted class). What am I doing wrong? all the best --cjc Traceback (most recent call last): File "libpetsc4py/libpetsc4py.pyx", line 1343, in libpetsc4py.PCApply_Python File "/Users/colincotter/firedrake/src/firedrake/firedrake/preconditioners/assembled.py", line 114, in apply push_appctx(dm, self._ctx_ref) AttributeError: 'Shifted' object has no attribute '_ctx_ref' The above exception was the direct cause of the following exception: SystemError: <built-in method insert of list object at 0x1125f5548> returned a result with an error set Exception ignored in: 'petsc4py.PETSc.traceback' SystemError: <built-in method insert of list object at 0x1125f5548> returned a result with an error set class Shifted(AuxiliaryOperatorPC): def form(self, pc, test, trial): ur, ui = split(trial) vr, vi = split(test) hrP = tau*H/(arP**2 + aiP**2)*(arP*div(ur) + aiP*div(ui)) hiP = tau*H/(arP**2 + aiP**2)*(-aiP*div(ur) + arP*div(ui)) aP = ( inner(arP*ur,vr) - inner(aiP*ui, vr) - tau*inner(f*perp(ur),vr) + tau*g*inner(hr,div(vr)) + inner(arP*ui,vi) + inner(aiP*ur, vi) - tau*inner(f*perp(ui),vi) + tau*g*inner(hi,div(vi)) )*dx bcs = None return (aP, bcs)

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