I converted in this way,
import numpy as np
import ufl
from petsc4py import PETSc
from slepc4py import SLEPc
from mpi4py import MPI
from dolfinx import mesh, fem
import dolfinx
import dolfinx.fem.petsc
Check for PETSc and SLEPc
if not hasattr(PETSc, ‘Mat’):
print(“PETSc is not available. Exiting.”)
exit()
if not hasattr(SLEPc, ‘EPS’):
print(“SLEPc is not available. Exiting.”)
exit()
Create mesh
width = 1.0
height = 0.5
mesh = mesh.create_rectangle(MPI.COMM_WORLD, [[0.0, 0.0], [width, height]], [8, 4], mesh.CellType.triangle)
Define function space
V = fem.FunctionSpace(mesh, (“Nedelec 1st kind H(curl)”, 2))
Define trial and test functions
u = ufl.TrialFunction(V)
v = ufl.TestFunction(V)
Define the forms
s = ufl.inner(ufl.curl(v), ufl.curl(u)) * ufl.dx
t = ufl.inner(v, u) * ufl.dx
L = ufl.inner(ufl.as_vector((0.0, 0.0)), v) * ufl.dx
Define boundary condition
zero = PETSc.ScalarType((0, 0))
bc = fem.dirichletbc(zero, fem.locate_dofs_geometrical(V, lambda x: np.full(x.shape[1], True)), V)
Assemble the stiffness matrix (S) and mass matrix (T)
A = dolfinx.fem.petsc.assemble_matrix(fem.form(s), bcs=[bc])
A.assemble()
B = dolfinx.fem.petsc.assemble_matrix(fem.form(t), bcs=[bc])
B.assemble()
Convert assembled matrices to PETSc.Mat
A_petsc = A
B_petsc = B
Solve the eigensystem using SLEPc
eigensolver = SLEPc.EPS().create()
eigensolver.setOperators(A_petsc, B_petsc)
eigensolver.setProblemType(SLEPc.EPS.ProblemType.GHEP)
eigensolver.setWhichEigenpairs(SLEPc.EPS.Which.SMALLEST_REAL)
eigensolver.solve()
Process and extract the eigenvalues
nconv = eigensolver.getConverged()
cutoff = None
count = 0
if nconv > 0:
for i in range(nconv):
lr, lc = eigensolver.getEigenvalue(i)
if lr > 1 and lc == 0:
cutoff = np.sqrt(lr)
_, _, rr, _ = eigensolver.getEigenpair(i)
u = fem.Function(V)
u.vector.setArray(rr)
u.vector.ghostUpdate(addv=PETSc.InsertMode.INSERT, mode=PETSc.ScatterMode.FORWARD)
print(f"Eigenvalue {i}: {cutoff}")
count += 1
if count > 4:
break
else:
print(“No eigenvalues found.”)
if cutoff is None:
print(“Unable to find dominant mode”)
else:
print(“Cutoff frequency:”, cutoff)
Blockquote
however, I faced with errors, and can you check the code?
ValueError Traceback (most recent call last)
Cell In[33], line 34
32 s = ufl.inner(ufl.curl(v), ufl.curl(u)) * ufl.dx
33 t = ufl.inner(v, u) * ufl.dx
—> 34 L = ufl.inner(ufl.as_vector((0.0, 0.0)), v) * ufl.dx
36 # Define boundary condition
37 zero = PETSc.ScalarType((0, 0))
File /usr/local/lib/python3.10/dist-packages/ufl/measure.py:386, in Measure.rmul(self, integrand)
384 domain, = domains
385 elif len(domains) == 0:
→ 386 raise ValueError(“This integral is missing an integration domain.”)
387 else:
388 raise ValueError(“Multiple domains found, making the choice of integration domain ambiguous.”)
ValueError: This integral is missing an integration domain.
Thank you
