def eigfind(mac):
n = mac.getSize()
Dt = Vec()
mac.getDiagonal(Dt)
Dt.reciprocal()
Dpt = PETSc.Mat().createAIJ([n, n])
Dpt.setUp()
Dpt.setDiagonal(Dt)
Dpt.assemblyBegin()
Dpt.assemblyEnd()
tarmat = Dpt * mac
def solve_eigensystem(Ac, problem_type=SLEPc.EPS.ProblemType.HEP):
# Create the result vectors
xr, xi = Ac.createVecs()
# Setup the eigensolver
E = SLEPc.EPS().create()
E.setOperators(Ac, None)
E.setDimensions(2, PETSc.DECIDE)
E.setProblemType(problem_type)
E.setFromOptions()
# Solve the eigensystem
E.solve()
print("")
its = E.getIterationNumber()
print("Number of iterations of the method: %i" % its)
sol_type = E.getType()
print("Solution method: %s" % sol_type)
nev, ncv, mpd = E.getDimensions()
print("Number of requested eigenvalues: %i" % nev)
tol, maxit = E.getTolerances()
print("Stopping condition: tol=%.4g, maxit=%d" % (tol, maxit))
nconv = E.getConverged()
print("Number of converged eigenpairs: %d" % nconv)
if nconv > 0:
print("")
print(" k ||Ax-kx||/||kx|| ")
print("----------------- ------------------")
for i in range(nconv):
k = E.getEigenpair(i, xr, xi)
error = E.computeError(i)
if k.imag != 0.0:
print(" %9f%+9f j %12g" % (k.real, k.imag, error))
else:
print(" %12f %12g" % (k.real, error))
print("")
solve_eigensystem(tarmat)
def makenew(Att, phere, emaxhere):
nhere = Att.getSize()
Dt = Vec()
Att.getDiagonal(Dt)
Dt.reciprocal()
Dpt = PETSc.Mat().createAIJ([nhere, nhere])
Dpt.setUp()
Dpt.setDiagonal(Dt)
Dpt.assemblyBegin()
Dpt.assemblyEnd()
omega = -4.0 / 3.0 / emaxhere
second = omega * Dpt * Att * phere
tmat = phere + second
return tmat