How to create complex Matrix by using PETSc.Mat()

[fredcool112]

After A.creator, I try to put numpy.matrix HH in PETSc.Mat(), like the following:

opts = PETSc.Options()
n = opts.getInt('n', 2**N)
A = PETSc.Mat()
A.create()
A.setSizes([n, n])
A.setFromOptions()
A.setUp()
for i in range(2**N):
        for j in range(2**N):
                A[i,j] = HH[i,j]
A.assemble()

Then it shows

test.py:171: ComplexWarning: Casting complex values to real discards the imaginary part
  A[i,j] = HH[i,j]

Please help me to put the complex number into PETSc.Mat()

Thank you

[Lisandro Dalcin]

Have you built PETSc and SLEPc with complex numbers (PETSc configure option --with-scalar-type=complex)?

[Lisandro Dalcin]

BTW, you should use A.setType(PETSc.Mat.Type.DENSE) after creation if you intend to store a dense matrix.

[Wu]

@dalcinl Hello, I have the same problem, but I install petsc and also petsc4py with conda python. It is only the following command:

conda install petsc4py

I would like to ask you here, how can I specify this complex configuration? Thanks

[Lisandro Dalcin]

The conda-forge builds do not yet support complex numbers. I'm planning to eventually add a complex variant of the PETSc package, but right now my efforts are directed towards supporting MPI variants.

[Ganesh Diwan]

@dalcinl I am trying to import complex matrices from Matlab in Python and use PETSc solvers with the help of petsc4py. I built my PETSc (libpetsc-complex-3.7.3) with the Synaptic and installed petsc4py with pip, both without any issues. I still end up with TypeError when using PETSc.Mat().createAIJ() or PETSc.Vec().createWithArray

TypeError: Cannot cast array data from dtype('complex128') to dtype('float64') according to the rule 'safe'

Do you reckon my PETSc or petsc4py is not properly configured or if I need to use a specific PETSc branch to be able to work with complex matrices/vectors. Tia.

[Lisandro Dalcin]

It seems that your petsc4py is not built with the right petsc-complex build. Please double check this way:

from petsc4py import PETSc
print(PETSc.ScalarType)

If PETSc.ScalarType is not a complex type, then you have to rebuild and reinstall petsc4py with the right PETSc build using complex numbers.

[Lisandro Dalcin]

You can also check using ldd on the PETSc.so extension module within the petsc4py installation.

[Lisandro Dalcin]

This issue tracker is intended to report issues, not general questions or help. A more appropriate place with much more visibility and chances of getting good advice is the petsc-users mailing list.