[petsc-users] ILU preconditioner

[Barry Smith]

   Unfortunately PETSc is restricted to working with only real or complex objects at one time and one cannot mix some real and some complex.

   Barry

On Jun 3, 2011, at 9:03 AM, Danesh Daroui wrote:

> 
> Hi,
> 
> In this case, can I create a preconditioner in double precision format
> and apply it to the system while I am using PETSc to solve a system of
> complex numbers? The reason is that I am solving equations in several
> iterations and I want to create an ILU-based preconditioner only on real
> part of my coefficient matrix because it is unchanged and I can create
> and store is once. The imaginary parts will change but they do not have
> big effect.
> 
> Regards,
> 
> D.
> 
> 
> On Tue, 2011-05-31 at 15:13 +0200, Jed Brown wrote:
>> On Tue, May 31, 2011 at 08:02, Danesh Daroui <danesh.daroui at ltu.se>
>> wrote:
>>        I have a complex system of equations and I use PETSc to solve
>>        the
>>        system. I also use MKL to create the preconditioner using ILU.
>>        The ILU
>>        preconditioner is created only on the real part of the
>>        coefficient
>>        matrix and is stored in CSR format with the data type of
>>        double
>>        precision. I wanted to ask if it is possible to use this
>>        preconditioner
>>        and pass it to PETSc in CSR format? Can it be used with PETSc
>>        complex
>>        solver although the preconditioner is in double precision
>>        format?
>> 
>> You can create a PCShell() that manages the factorization using MKL
>> and applies the preconditioner stored in whatever format MKL likes.
>> PETSc would not know that it is ILU or otherwise. It sounds like that
>> would do what you want.
> 
> 
>