def systems_and_preconditioners(mesh, X, z, order=1):
# Create a real analogue of our vector space for the wrapper preconditioner.
dirichlet = 'top|right|bottom|left'
X_real = ng.H1(mesh, order=order, dirichlet=dirichlet, complex=False)
# Test and trial functions for the original space.
u, v = X.TnT()
# Real trial and test functions.
ur, vr = X_real.TnT()
# Create a real analogue of the bilinear form a.
a_real = ng.BilinearForm(X_real)
a_real += ng.SymbolicBFI(ng.grad(ur) * ng.grad(vr))
a_real.Assemble()
# Initialize petsc prior to conswtructing preconditioners.
petsc.Initialize()
# Create a bilinear form and a preconditioner for each z.
zbas = []
precs = []
for k in range(len(z)):
# Create a bilinear form for the given z-value.
zba = ng.BilinearForm(X)
zba += ng.SymbolicBFI(z[k] * u * v - ng.grad(u) * ng.grad(v))
# Create a preconditioner for the given z-value.
mat_convert = petsc.PETScMatrix(a_real.mat, freedofs=X_real.FreeDofs())
real_pc = petsc.PETSc2NGsPrecond(mat=mat_convert,
name="real_pc",
petsc_options={"pc_type": "gamg"})
prec = WrapperPrec(real_pc)
# Assemble the given bilinear form.
zba.Assemble()
# Tack the bilinear forms and preconditioners onto their respective lists.
zbas += [zba]
precs += [prec]
return zbas, precs
gfu = GridFunction(fes)
rbm_vecs = list()
upart = gfu
for RBM in RBMS:
if dim == 3:
ucf = CoefficientFunction((RBM[0], RBM[1], RBM[2]))
else:
ucf = CoefficientFunction((RBM[0], RBM[1]))
upart.Set(ucf)
v = gfu.vec.CreateVector()
v.data = gfu.vec
rbm_vecs.append(v)
return rbm_vecs
petsc.Initialize()
mat_wrap = petsc.PETScMatrix(a.mat,
freedofs=V.FreeDofs(),
format=petsc.PETScMatrix.AIJ)
opts = {"ksp_type": "cg", "ksp_atol": 1e-30, "ksp_rtol": 1e-8, "pc_type": "ml"}
ksp = petsc.KSP(mat=mat_wrap,
name="someksp",
petsc_options=opts,
finalize=False)
ksp.GetMatrix().SetNearNullSpace(rb_modes(V))
# import ngs_amg
# mat_wrap = petsc.FlatPETScMatrix(a.mat, freedofs=V.FreeDofs())
# ngs_amg_opts = {"energy" : "alg", "comp_sm" : True, "force_comp_sm" : True, "max_cv" : 500, "ass_frac" : 0.15, "skip_ass" : 3}
# ngs_pc = ngs_amg.AMG_EL2(blf=a, freedofs=V.FreeDofs(), **ngs_amg_opts)
else:
ngm = NGMesh.Receive(comm)
mesh = Mesh(ngm)
V = H1(mesh, order=1, dirichlet='.*')
u, v = V.TnT()
a = BilinearForm(V)
a += SymbolicBFI(InnerProduct(grad(u), grad(v)))
f = LinearForm(V)
f += SymbolicLFI(v)
f.Assemble()
gfu = GridFunction(V)
# c = Preconditioner(a, 'bddc')
a.Assemble()
ngp.Initialize()
wrapped_mat = ngp.PETScMatrix(a.mat,
freedofs=V.FreeDofs(),
format=ngp.PETScMatrix.IS_AIJ)
# gives access to the petsc4py mat
p4p_mat = wrapped_mat.GetPETScMat()
if comm.size > 1:
p4p_mat.convert("mpiaij")
# this is a wrapper around a KSP
wrapped_ksp = ngp.KSP(mat=wrapped_mat,
name="someksp",
petsc_options={
"ksp_type": "cg",
I = Id(mesh.dim)
F = I + u.Deriv() # attention: row .. component, col .. derivative
C = F * F.trans
factor = Parameter(1.0)
a = BilinearForm(V, symmetric=False)
a += SymbolicEnergy( NeoHook (C).Compile(False) )
a += SymbolicEnergy( (-factor * InnerProduct(force,u) ).Compile(False) )
gfu = GridFunction(V)
gfu2 = GridFunction(V)
poo = dict()
#poo = {"info" : ""}
petsc.Initialize(**poo)
petsc_options = {"pc_type" : "none",
"ksp_type" : "cg",
"ksp_atol" : 1e-30,
"ksp_rtol" : 1e-8,
"ksp_max_it" : 1000,
# "ksp_view" : "",
# "ksp_monitor" : "",
# "ksp_converged_reason" : "",
# "snes_view" : "",
# "snes_monitor" : "",
# "snes_converged_reason" : "",
"snes_max_it" : 50,
"snes_linesearch_type" : "basic" }
snes = petsc.SNES(a, name="mysnes", petsc_options=petsc_options, mode = petsc.SNES.JACOBI_MAT_MODE.FLAT)