[petsc-users] teething troubles / MatView() fails silently for transposed seqaij matrix

[Bryan Jurish]

hi Junchao,

thanks for the hint... I'll give it try when I'm back on my work machine on
Monday.

marmosets,
 Bryan

--
typed with my opposable thumbs!

On Fri, Apr 13, 2018, 15:46 Junchao Zhang <jczhang at mcs.anl.gov> wrote:

> Looks like MatCreateTranspose does not form the transpose, See the notes
> here
> <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateTranspose.html>. You
> may want to use MatTranspose
> <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatTranspose.html>
> .
>
> --Junchao Zhang
>
> On Fri, Apr 13, 2018 at 7:25 AM, Bryan Jurish <moocow.bovine at gmail.com>
> wrote:
>
>> morning all,
>>
>> Apologies for what is very probably a boundlessly stupid question.  I've
>> just begun exploring PETSc, but find myself stumped by a pretty trivial
>> task.  I would like to load a real binary seqaij matrix and save its
>> transposition (also as a binary  seqaij matrix) to a different file.
>> I've tried PETSc v3.7.5 on debian stretch and v3.6.2 on ubuntu 16.04, both
>> with no joy.  In both cases the program runs to completion and exits
>> normally, but no output file ("INFILE.T") is written.  Stepping through
>> MatView() with the debugger, it seems that (mat->ops->view) is not set for
>> the transposition I created with MatCreateTranspose(). I suppose I could
>> always loop over the input indices and assemble a physical transposition
>> manually, but that rather defeats the purpose of the exercise... can anyone
>> here tell me what I'm doing wrong (almost certainly something fundamental
>> and obvious)?  Thanks in advance for any help you can provide.
>>
>> marmosets,
>>   Bryan
>>
>> ::: BEGIN MINIMUM BROKEN EXAMPLE :::
>> /*-*- Mode: C -*-*/
>>
>> static char help[] = "Transposes a matrix in BINARY format\n\
>> Input parameters are:\n\
>>   -file INFILE     : input matrix in binary format\n\
>>   -out OUTFILE     : write output to OUTFILE (default=INFILE.T)\n\
>> ";
>>
>>
>> #include <petscmat.h>
>>
>> //-- handle v3.7 API change
>> #if PETSC_VERSION_MAJOR>3 || (PETSC_VERSION_MAJOR==3 &&
>> PETSC_VERSION_MINOR>=7)
>>   #define OPTIONS_NULL NULL,NULL
>> #else
>>   #define OPTIONS_NULL NULL
>> #endif
>>
>>
>> #undef __FUNCT__
>> #define __FUNCT__ "main"
>> int main(int argc,char **args)
>> {
>>   Mat            A,B;
>>   char           infile[PETSC_MAX_PATH_LEN], outfile[PETSC_MAX_PATH_LEN];
>>   PetscErrorCode ierr;
>>   PetscInt       m,n;
>>   PetscViewer    view;
>>   PetscBool      flg_file,flg_out;
>>   PetscMPIInt    size;
>>
>>   PetscInitialize(&argc,&args,(char*)0,help);
>>   ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRQ(ierr);
>>   ierr = PetscPrintf(PETSC_COMM_WORLD," MPI_Comm_size reports %d
>> process(es) available.\n", size);CHKERRQ(ierr);
>>   if (size != 1) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP,"This is a
>> uniprocessor operation only!");
>>
>>   /*-- Read in source matrix, binary --*/
>>   ierr =
>> PetscOptionsGetString(OPTIONS_NULL,"-file",infile,PETSC_MAX_PATH_LEN,&flg_file);CHKERRQ(ierr);
>>   if (!flg_file) SETERRQ(PETSC_COMM_WORLD,1,"Must specify a file name
>> with the -file option");
>>
>> #if defined(PETSC_USE_COMPLEX)
>>   ierr = PetscPrintf(PETSC_COMM_WORLD," Reading COMPLEX matrix from
>> binary file `%s'...\n", infile);CHKERRQ(ierr);
>> #else
>>   ierr = PetscPrintf(PETSC_COMM_WORLD," Reading REAL matrix from binary
>> file `%s'...\n", infile);CHKERRQ(ierr);
>> #endif
>>   ierr =
>> PetscViewerBinaryOpen(PETSC_COMM_WORLD,infile,FILE_MODE_READ,&view);CHKERRQ(ierr);
>>   ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
>>   ierr = MatSetFromOptions(A);CHKERRQ(ierr);
>>   ierr = MatLoad(A,view);CHKERRQ(ierr);
>>   ierr = PetscViewerDestroy(&view);CHKERRQ(ierr);
>>   //
>>   ierr = MatGetSize(A,&m,&n);
>>   ierr = PetscPrintf(PETSC_COMM_WORLD," Read input matrix of size
>> (m=%D,n=%D)\n", m,n);CHKERRQ(ierr);
>>
>>   /*-- guts: transpose --*/
>>   ierr = PetscPrintf(PETSC_COMM_WORLD," Performing transposition
>> (constructive)\n");CHKERRQ(ierr);
>>   ierr = MatCreateTranspose(A,&B);CHKERRQ(ierr);
>>
>>   /*-- dump transposed matrix --*/
>>   ierr =
>> PetscOptionsGetString(OPTIONS_NULL,"-out",outfile,PETSC_MAX_PATH_LEN,&flg_out);CHKERRQ(ierr);
>>   if (!flg_out) {
>>     strcpy(outfile,infile);
>>     strcat(outfile,".T");
>>   }
>>   ierr = PetscPrintf(PETSC_COMM_SELF," Writing transposed matrix in
>> binary format to '%s' ...\n", outfile);CHKERRQ(ierr);
>>   ierr =
>> PetscViewerBinaryOpen(PETSC_COMM_SELF,outfile,FILE_MODE_WRITE,&view);CHKERRQ(ierr);
>>   ierr = MatView(B,view);CHKERRQ(ierr);
>>
>>   /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>>    * output file is not written: much wailing and gnashing of teeth
>>    * !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>>    */
>>
>>   /*-- cleanup --*/
>>   ierr = MatDestroy(&A);CHKERRQ(ierr);
>>   ierr = MatDestroy(&B);CHKERRQ(ierr);
>>   ierr = PetscViewerDestroy(&view);CHKERRQ(ierr);
>>   ierr = PetscFinalize();
>>   return 0;
>> }
>> ::: END MINIMUM BROKEN EXAMPLE :::
>>
>> --
>> Bryan Jurish                           "There is *always* one more bug."
>> moocow.bovine at gmail.com         -Lubarsky's Law of Cybernetic Entomology
>>
>
>
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