[petsc-users] Matrix exponential

[Paul, Sanku]

Hi Jose,

   I tried to install
ml -* foss/2019b Python SciPy-bundle/2019.10-Python-3.7.4
virtualenv slepc4py
cd slepc4py
source bin/activate
pip install numpy mpi4py cython

export PETSC_CONFIGURE_OPTIONS="--with-scalar-type=complex"

export PETSC_DIR=/path/to/petsc PETSC_ARCH=your-arch-name

pip install petsc petsc4py
pip install slepc slepc4py

But still facing problem with complex matrices. Please help me to fix this.

Thanks,
Sanku


________________________________
From: Paul, Sanku <paulsank at msu.edu>
Sent: Friday, September 3, 2021 7:39 PM
To: Jose E. Roman <jroman at dsic.upv.es>
Cc: PETSc <petsc-users at mcs.anl.gov>
Subject: Re: [petsc-users] Matrix exponential

Hi Jose,

   I could now do matrix exponential but facing a problem with a complex matrix. In particular, I want to do \exp(-itH), where H is a Hamiltonian.  How to implement this?

Thanks,
Sanku
________________________________
From: Jose E. Roman <jroman at dsic.upv.es>
Sent: Friday, September 3, 2021 2:53 PM
To: Paul, Sanku <paulsank at msu.edu>
Cc: PETSc <petsc-users at mcs.anl.gov>
Subject: Re: [petsc-users] Matrix exponential

Please always reply to the list (Reply-All), not to myself.

You should be able to convert from a scipy sparse matrix to a PETSc matrix via PETSc.Mat().createAIJWithArrays(). Don't know how if there is any example in the petsc4py documentation.

Jose


> El 3 sept 2021, a las 20:26, Paul, Sanku <paulsank at msu.edu> escribió:
>
> Dear Jose,
>
>    Thank you very much for your help. I have another question can we just simply pass a sparse.csr.matrix to A. For instance, if B is the sparse.csr.matrix can we do A=B.copy(). Or do I have to do it in a different way?
>
> Best,
> Sanku
> From: Jose E. Roman <jroman at dsic.upv.es>
> Sent: Friday, September 3, 2021 2:13 PM
> To: Paul, Sanku <paulsank at msu.edu>
> Cc: petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>
> Subject: Re: [petsc-users] Matrix exponential
>
> You should either create the FN object and then
>
> E.setFN(F)
>
> or extract the FN object and assign to a variable
>
> F = E.getFN()
>
> You can see an example in $SLEPC_DIR/src/binding/slepc4py/demo/ex6.py
>
>
> Jose
>
>
> > El 3 sept 2021, a las 19:53, Paul, Sanku <paulsank at msu.edu> escribió:
> >
> > Dear Sir/Ma'am,
> >
> >    I am trying to use SLEPc to calculate matrix exponential in my python code but I am not getting the correct result. I have attached the code. Could you let me know what I am doing wrong. This is my first time using SLEPc. So, I would like to ask you if you could send me a tutorial on matrix exponential using SLEPc in python code.
> >
> > Best,
> > Sanku
> > <ex2.py>

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