[petsc-users] Help with Integrating PETSc into Fortran Groundwater Flow Simulation Code

[Barry Smith]

Instead of 

    call PCCreate(PETSC_COMM_WORLD, pc, ierr)
    call PCSetType(pc, PCILU,ierr) ! Choose a preconditioner type (ILU)
    call KSPSetPC(ksp, pc,ierr)  ! Associate the preconditioner with the KSP solver

do

    call KSPGetPC(ksp,pc,ierr)
    call PCSetType(pc, PCILU,ierr)

Do not call KSPSetUp(). It will be taken care of automatically during the solve



> On Dec 20, 2023, at 8:52 PM, Shatanawi, Sawsan Muhammad via petsc-users <petsc-users at mcs.anl.gov> wrote:
> 
> Hello, 
> I don't think that I set preallocation values when I created the matrix, would you please have look at my code. It is just the petsc related part from my code.
> I was able to fix some of the error messages. Now I have a new set of error messages related to the KSP solver (attached)
> 
> I appreciate your help​
> 
> Sawsan
> From: Mark Adams <mfadams at lbl.gov <mailto:mfadams at lbl.gov>>
> Sent: Wednesday, December 20, 2023 6:44 AM
> To: Shatanawi, Sawsan Muhammad <sawsan.shatanawi at wsu.edu <mailto:sawsan.shatanawi at wsu.edu>>
> Cc: petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov> <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>>
> Subject: Re: [petsc-users] Help with Integrating PETSc into Fortran Groundwater Flow Simulation Code
>  
> [EXTERNAL EMAIL]
> Did you set preallocation values when you created the matrix?
> Don't do that.
> 
> On Wed, Dec 20, 2023 at 9:36 AM Shatanawi, Sawsan Muhammad <sawsan.shatanawi at wsu.edu <mailto:sawsan.shatanawi at wsu.edu>> wrote:
> Hello, 
> 
> I am trying to create a sparse matrix( which is as I believe a zero matrix) then adding some nonzero elements to it over a loop, then assembling it 
> 
> Get Outlook for iOS <https://urldefense.com/v3/__https://aka.ms/o0ukef__;!!JmPEgBY0HMszNaDT!uUJ_jeYf45gcXDGR_PeMjhU7hbd_fKcXJPn0pM9eb-YQihKNYuXMYM9x-hglsbXsCFIwNBWgHXdetHODupsOloE$>
> From: Mark Adams <mfadams at lbl.gov <mailto:mfadams at lbl.gov>>
> Sent: Wednesday, December 20, 2023 2:48 AM
> To: Shatanawi, Sawsan Muhammad <sawsan.shatanawi at wsu.edu <mailto:sawsan.shatanawi at wsu.edu>>
> Cc: petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov> <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>>
> Subject: Re: [petsc-users] Help with Integrating PETSc into Fortran Groundwater Flow Simulation Code
>  
> [EXTERNAL EMAIL]
> I am guessing that you are creating a matrix, adding to it, finalizing it ("assembly"), and then adding to it again, which is fine, but you are adding new non-zeros to the sparsity pattern.
> If this is what you want then you can tell the matrix to let you do that.
> Otherwise you have a bug.
> 
> Mark
> 
> On Tue, Dec 19, 2023 at 9:50 PM Shatanawi, Sawsan Muhammad via petsc-users <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>> wrote:
> Hello everyone,
> 
> I hope this email finds you well.
> 
>  My Name is Sawsan Shatanawi, and I am currently working on developing a Fortran code for simulating groundwater flow in a 3D system. The code involves solving a nonlinear system, and I have created the matrix to be solved using the PCG solver and Picard iteration. However, when I tried to assign it as a PETSc matrix I started getting a lot of error messages.
> 
> I am kindly asking if someone can help me, I would be happy to share my code with him/her.
> 
> Please find the attached file contains a list of errors I have gotten
> 
> Thank you in advance for your time and assistance.
> Best regards,
> 
>  Sawsan
> 
> 
> <Matrix_RHS.F90><out.txt><solver.F90>

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