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    Here comes the continuation of the story:<br>
    <br>
    [24]PETSC ERROR: --------------------- Error Message
    ------------------------------------<br>
    [24]PETSC ERROR: Object is in wrong state!<br>
    [24]PETSC ERROR: Must call MatXXXSetPreallocation() or MatSetUp() on
    argument 1 "mat" before MatScaleSystem()!<br>
    [24]PETSC ERROR:
    ------------------------------------------------------------------------<br>
    [24]PETSC ERROR: Petsc Development HG revision:
    a4dae06b4d05ef5b78a9a9aa2cbc31b2b158834f  HG Date: Wed Feb 08
    11:29:52 2012 -0600<br>
    [24]PETSC ERROR: See docs/changes/index.html for recent updates.<br>
    [24]PETSC ERROR: See docs/faq.html for hints about trouble shooting.<br>
    [24]PETSC ERROR: See docs/index.html for manual pages.<br>
    [24]PETSC ERROR:
    ------------------------------------------------------------------------<br>
    [24]PETSC ERROR: /home/eprog on a openmpi-i named node226 by
    agrayver Wed Feb  8 21:24:13 2012<br>
    [24]PETSC ERROR: Libraries linked from
    /home/lib/petsc-dev/openmpi-intel-complex-debug-f-mkl/lib<br>
    [24]PETSC ERROR: Configure run at Wed Feb  8 20:51:18 2012<br>
    [24]PETSC ERROR:
    ------------------------------------------------------------------------<br>
    [24]PETSC ERROR: MatScaleSystem() line 932 in
    /home/lib/petsc-dev/src/mat/interface/matrix.c<br>
    [24]PETSC ERROR: PCPreSolve() line 1389 in
    /home/lib/petsc-dev/src/ksp/pc/interface/precon.c<br>
    [24]PETSC ERROR: KSPSolve() line 410 in
    /home/lib/petsc-dev/src/ksp/ksp/interface/itfunc.c<br>
    <br>
    It happens within the CG solver with the system matrix which is
    created like this:<br>
    call
MatCreateShell(MPI_COMM_WORLD,mlocal,nlocal,N,N,PETSC_NULL_INTEGER,H,ierr);CHKERRQ(ierr)<br>
    <br>
    On 08.02.2012 21:28, Alexander Grayver wrote:
    <blockquote cite="mid:4F32DB0B.4050002@gfz-potsdam.de" type="cite">
      <meta content="text/html; charset=ISO-8859-1"
        http-equiv="Content-Type">
      Hong,<br>
      <br>
      Everything seems to be working well so far.<br>
      I would say there is nothing to acknowledge, but I don't mind...<br>
      <br>
      Please let me know if there will be support for mpiaij_mpidense.<br>
      <br>
      Thanks for this great support.<br>
      <br>
      On 08.02.2012 18:43, Hong Zhang wrote:
      <blockquote
cite="mid:CAGCphBsuHe2wKMN1ZpjrNkv1Ev6vT3cuDSTHWNoUdmPu0Zh5yg@mail.gmail.com"
        type="cite">Alexander:
        <div>Recently, we add error flags in petsc-dev
          requiring MatXXXSetPreallocation() for many matrix creation
          routines.</div>
        <div>I've updated relevant routines for your code, and add your
          contributed testing code as a petsc example with acknowledge:</div>
        <div>petsc-dev/src/mat/examples/tests/ex165.c</div>
        <div>Let me know if you do not want your name to be acknowledge
          in the example.</div>
        <div><br>
        </div>
        <div>I tested ex165 with your A and B in sequential (np=1) and
          parallel (np=2, 6):</div>
        <div>mpiexec -n <np> ./ex165 -fA A.dat -fB B.dat -view_C</div>
        <div><br>
        </div>
        <div>Checking the size of output file C.dat, I see the
          sequential run and parallel run give identical bit size. </div>
        <div>Please get the updated petsc-dev and test it. Let me know
          if you still have problem.</div>
        <div><br>
        </div>
        <div>It is inefficient to compute C=A^T*B via MatTranspose() and
          MatMatMult().</div>
        <div>I'll see if I can write a C=A^T*B  for mpiaij_mpidense. </div>
        <div><br>
        </div>
        <div>Hong</div>
        <div>
          <div class="gmail_quote">
            <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
              0.8ex; border-left: 1px solid rgb(204, 204, 204);
              padding-left: 1ex;">
              <div bgcolor="#ffffff" text="#000000"><br>
                In addition, I changed my code and form A^T explicitly
                (to avoid previous error) and I got another one:
                <div class="im"><br>
                  <br>
                  [1]PETSC ERROR: --------------------- Error Message
                  ------------------------------------<br>
                </div>
                [1]PETSC ERROR: Object is in wrong state!<br>
                [1]PETSC ERROR: Must call MatXXXSetPreallocation() or
                MatSetUp() on argument 1 "mat" before
                MatAssemblyBegin()!<br>
                [1]PETSC ERROR:
                ------------------------------------------------------------------------<br>
                [1]PETSC ERROR: Petsc Development HG revision:
                249597282bcb6a1051042a9fdfa5705679ed4f18  HG Date: Tue
                Feb 07 09:44:23 2012 -0600<br>
                [1]PETSC ERROR: See docs/changes/index.html for recent
                updates.<br>
                [1]PETSC ERROR: See docs/faq.html for hints about
                trouble shooting.<br>
                [1]PETSC ERROR: See docs/index.html for manual pages.<br>
                [1]PETSC ERROR:
                ------------------------------------------------------------------------<br>
                [1]PETSC ERROR: solveTest on a openmpi-i named glic1 by
                agrayver Wed Feb  8 13:06:45 2012<br>
                [1]PETSC ERROR: Libraries linked from
                /home/lib/petsc-dev/openmpi-intel-complex-debug-f-mkl/lib<br>
                [1]PETSC ERROR: Configure run at Tue Feb  7 18:19:58
                2012<br>
                [1]PETSC ERROR: Configure options
                --with-petsc-arch=openmpi-intel-complex-debug-f-mkl
                --with-fortran-interfaces=1 --download-superlu
                --download-superlu_dist --download-mumps
                --download-parmetis --download-ptscotch --download-metis
                --with-scalapack-lib=/opt/intel/Compiler/11.1/072/mkl/lib/em64t/libmkl_scalapack_lp64.a


                --with-scalapack-include=/opt/intel/Compiler/11.1/072/mkl/include


                --with-blacs-lib=/opt/intel/Compiler/11.1/072/mkl/lib/em64t/libmkl_blacs_openmpi_lp64.a


                --with-blacs-include=/opt/intel/Compiler/11.1/072/mkl/include


                --with-mpi-dir=/opt/mpi/intel/openmpi-1.4.2
                --with-scalar-type=complex
                --with-blas-lapack-lib="[/opt/intel/Compiler/11.1/072/mkl/lib/em64t/libmkl_intel_lp64.a,/opt/intel/Compiler/11.1/072/mkl/lib/em64t/libmkl_intel_thread.a,/opt/intel/Compiler/11.1/072/mkl/lib/em64t/libmkl_core.a,/opt/intel/Compiler/11.1/072/lib/intel64/libiomp5.a]"


                --with-precision=double --with-x=0<br>
                [1]PETSC ERROR:
                ------------------------------------------------------------------------<br>
                [1]PETSC ERROR: MatAssemblyBegin() line 4795 in
                /home/lib/petsc-dev/src/mat/interface/matrix.c<br>
                [1]PETSC ERROR: MatMatMultSymbolic_MPIAIJ_MPIDense()
                line 638 in
                /home/lib/petsc-dev/src/mat/impls/aij/mpi/mpimatmatmult.c<br>
                [1]PETSC ERROR: MatMatMult_MPIAIJ_MPIDense() line 594 in
/home/lib/petsc-dev/src/mat/impls/aij/mpi/mpimatmatmult.c<br>
                [1]PETSC ERROR: MatMatMult() line 8618 in
                /home/lib/petsc-dev/src/mat/interface/matrix.c
                <div>
                  <div class="h5"><br>
                    <br>
                    On 08.02.2012 17:45, Hong Zhang wrote:
                    <blockquote type="cite">Alexander :
                      <div>I can repeat the crash, and am working on it.</div>
                      <div>I'll let you know after the bug is fixed.</div>
                      <div><br>
                      </div>
                      <div>Thanks for your patience,</div>
                      <div>Hong<br>
                        <div class="gmail_quote">
                          <blockquote class="gmail_quote" style="margin:
                            0pt 0pt 0pt 0.8ex; border-left: 1px solid
                            rgb(204, 204, 204); padding-left: 1ex;">
                            <div bgcolor="#ffffff" text="#000000"> <br>
                              It seems now I know why I used
                              MAT_REUSE_MATRIX and preallocated matrix.<br>
                              I removed MatCreateMPIAIJ() and use just
                              MatTranspose with MAT_INITIAL_MATRIX.<br>
                              As a consequence I get hundreds of errors
                              like:<br>
                              <br>
                              [30]PETSC ERROR: MatSetValues_MPIAIJ()
                              line 538 in
                              /home/mt/agrayver/lib/petsc-dev/src/mat/impls/aij/mpi/mpiaij.c<br>
                              [30]PETSC ERROR: MatAssemblyEnd_MPIAIJ()
                              line 653 in
                              /home/mt/agrayver/lib/petsc-dev/src/mat/impls/aij/mpi/mpiaij.c<br>
                              [30]PETSC ERROR: MatAssemblyEnd() line
                              4978 in
                              /home/mt/agrayver/lib/petsc-dev/src/mat/interface/matrix.c<br>
                              [30]PETSC ERROR: MatTranspose_MPIAIJ()
                              line 2061 in
                              /home/mt/agrayver/lib/petsc-dev/src/mat/impls/aij/mpi/mpiaij.c<br>
                              [30]PETSC ERROR: MatTranspose() line 4397
                              in
/home/mt/agrayver/lib/petsc-dev/src/mat/interface/matrix.c<br>
                              [31]PETSC ERROR: ---------------------
                              Error Message
                              ------------------------------------<br>
                              [31]PETSC ERROR: Argument out of range!<br>
                              [31]PETSC ERROR: New nonzero at
                              (1659,53337) caused a malloc!<br>
                              <br>
                              Ans this is the lastest petsc-dev
                              revision. <br>
                              I know there were some changes in
                              petsc-dev concerning this issue. <br>
                              Can you give me a hint how to avoid this?<br>
                              <br>
                              As for why I need C=A^T*B. This product is
                              used further as a system matrix for LSQR
                              solver. The largest dimension is on the
                              order of 10^6<br>
                              Since I form A and B myself I can, of
                              course, form A^T explicitly, but I thought
                              I would first implement everything as it
                              is written down on paper and then optimize
                              once it works (I thought it's easier way).
                              <div>
                                <div><br>
                                  <br>
                                  On 07.02.2012 20:44, Hong Zhang wrote:
                                  <blockquote type="cite">Alexander,
                                    <div>I'm curious about why do you
                                      need parallel C=A^T*B?</div>
                                    <div>How large your matrices are?</div>
                                    <div><br>
                                    </div>
                                    <div>In petsc-dev, we
                                      have MatTransposeMatMult() for
                                      mpiaij and mpiaij, but not mpiaij
                                      and mpidense.</div>
                                    <div>We may add support
                                      of MatTransposeMatMult_MPIAIJ_MPIDense()
                                      if there is such need.</div>
                                    <div><br>
                                    </div>
                                    <div>Hong</div>
                                    <div><br>
                                      <br>
                                      <div class="gmail_quote">On Tue,
                                        Feb 7, 2012 at 1:18 PM, <a
                                          moz-do-not-send="true"
                                          href="mailto:agrayver@gfz-potsdam.de"
                                          target="_blank">agrayver@gfz-potsdam.de</a>
                                        <span dir="ltr"><<a
                                            moz-do-not-send="true"
                                            href="mailto:agrayver@gfz-potsdam.de"
                                            target="_blank">agrayver@gfz-potsdam.de</a>></span>
                                        wrote:<br>
                                        <blockquote class="gmail_quote"
                                          style="margin: 0pt 0pt 0pt
                                          0.8ex; border-left: 1px solid
                                          rgb(204, 204, 204);
                                          padding-left: 1ex;">Hong,<br>
                                          <br>
                                          Thanks for explanation. I will
                                          try this tomorrow. Good to
                                          have this stuff in the help
                                          now.<br>
                                          <br>
                                          And sorry for misleading you
                                          initially.<br>
                                          <br>
                                          Regards,<br>
                                          Alexander
                                          <div>
                                            <div><br>
                                              <br>
                                              <div>----- Reply message
                                                -----<br>
                                                From: "Hong Zhang" <<a
                                                  moz-do-not-send="true"
href="mailto:hzhang@mcs.anl.gov" target="_blank">hzhang@mcs.anl.gov</a>><br>
                                                To: "For users of the
                                                development version of
                                                PETSc" <<a
                                                  moz-do-not-send="true"
href="mailto:petsc-dev@mcs.anl.gov" target="_blank">petsc-dev@mcs.anl.gov</a>><br>
                                                Subject: [petsc-dev]
                                                MatMatMult gives
                                                different results<br>
                                                Date: Tue, Feb 7, 2012
                                                19:09<br>
                                                <br>
                                              </div>
                                              <br>
                                              Alexander :
                                              <div class="gmail_quote">
                                                <blockquote
                                                  class="gmail_quote"
                                                  style="margin: 0pt 0pt
                                                  0pt 0.8ex;
                                                  border-left: 1px solid
                                                  rgb(204, 204, 204);
                                                  padding-left: 1ex;">
                                                  <div bgcolor="#ffffff"
                                                    text="#000000"><br>
                                                    There is something I
                                                    didn't get yet, I
                                                    hope you could
                                                    clarify it. <br>
                                                    <br>
                                                    So, when I use flag
                                                    MAT_INITIAL_MATRIX
                                                    in test program it
                                                    works fine.<br>
                                                  </div>
                                                </blockquote>
                                                <div>Good to know :-)</div>
                                                <div> </div>
                                                <blockquote
                                                  class="gmail_quote"
                                                  style="margin: 0pt 0pt
                                                  0pt 0.8ex;
                                                  border-left: 1px solid
                                                  rgb(204, 204, 204);
                                                  padding-left: 1ex;">
                                                  <div bgcolor="#ffffff"
                                                    text="#000000"> If I
                                                    put this flag in my
                                                    original program I
                                                    get dozens of
                                                    exceptions like:<br>
                                                    [42]PETSC ERROR:
                                                    Argument out of
                                                    range!<br>
                                                    [42]PETSC ERROR: New
                                                    nonzero at
                                                    (1336,153341) caused
                                                    a malloc!<br>
                                                  </div>
                                                </blockquote>
                                                <div>You cannot do </div>
                                                <div> <span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatCreateMPIAIJ()</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatTranspose(A,MAT_INITIAL_MATRIX,&AT);</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;"><br>
                                                  </span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatCreateMPIAIJ()


                                                    creates AT and
                                                    preallocates
                                                    approximate
                                                    nonzeros, which does
                                                    not match exactly
                                                    the nonzeros in </span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatTranspose(A,MAT_INITIAL_MATRIX,&AT);</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatTranspose(A,MAT_INITIAL_MATRIX,&AT)



                                                    creates matrix AT
                                                    and sets correct
                                                    nonzero pattern and
                                                    values in AT. </span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatTranspose()


                                                    only takes in "</span><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MAT_INITIAL_MATRIX"


                                                    - for a new AT,</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">and

                                                    "MAT_REUSE_MATRIX"
                                                    when AT is created
                                                    with </span><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatTranspose(A,MAT_INITIAL_MATRIX,&AT)</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">and

                                                    reuse for updating
                                                    its values (not
                                                    nonzero patten).</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;"><br>
                                                  </span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">I'm

                                                    updating petsc help
                                                    menu on </span><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">MatTranspose().


                                                    Thanks for the
                                                    report.</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;"><br>
                                                  </span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;">Hong</span></div>
                                                <div><span
                                                    style="border-collapse:
                                                    collapse; color:
                                                    rgb(80, 0, 80);
                                                    font-family:
                                                    arial,sans-serif;
                                                    font-size: 14px;"><br>
                                                  </span></div>
                                                <blockquote
                                                  class="gmail_quote"
                                                  style="margin: 0pt 0pt
                                                  0pt 0.8ex;
                                                  border-left: 1px solid
                                                  rgb(204, 204, 204);
                                                  padding-left: 1ex;">
                                                  <div bgcolor="#ffffff"
                                                    text="#000000"> <br>
                                                    I changed this flag
                                                    to MAT_REUSE_MATRIX
                                                    and exceptions
                                                    disappeared, but
                                                    result is incorrect
                                                    again (same as for
                                                    MAT_IGNORE_MATRIX) 
                                                    <br>
                                                    I tried test program
                                                    with
                                                    MAT_REUSE_MATRIX and
                                                    it also gives
                                                    different matrix
                                                    product.<br>
                                                    <br>
                                                    Since there is no
                                                    description of
                                                    MatReuse structure
                                                    for MatTranspose
                                                    it's a bit confusing
                                                    what to expect from
                                                    it. <br>
                                                    <div>
                                                      <div> <br>
                                                        <blockquote
                                                          type="cite">
                                                          <div
                                                          class="gmail_quote">
                                                          <blockquote
                                                          class="gmail_quote"
                                                          style="margin:
                                                          0pt 0pt 0pt
                                                          0.8ex;
                                                          border-left:
                                                          1px solid
                                                          rgb(204, 204,
                                                          204);
                                                          padding-left:
                                                          1ex;">
                                                          <div
                                                          bgcolor="#ffffff"
                                                          text="#000000">
                                                          <div>
                                                          <blockquote
                                                          type="cite">
                                                          <div>
                                                          <div
                                                          class="gmail_quote">
                                                          <div><br>
                                                          </div>
                                                          <div>Do you
                                                          mean 'Cm =
                                                          A'*B;'? </div>
                                                          <div>'Cm =
                                                          A.'*B;' gives
                                                          component-wise
                                                          matrix
                                                          product, not
                                                          matrix
                                                          product.</div>
                                                          </div>
                                                          </div>
                                                          </blockquote>
                                                          <br>
                                                          </div>
                                                          .' operator
                                                          means
                                                          non-Hermitian
                                                          transpose.
                                                          That is what I
                                                          get with
                                                          MatTranspose
                                                          (in contrast
                                                          with
                                                          MatHermitianTranspose)<br>
                                                          component-wise
                                                          matrix product
                                                          would be .*</div>
                                                          </blockquote>
                                                          <div>You are
                                                          correct.</div>
                                                          <div><br>
                                                          </div>
                                                          <div>Hong </div>
                                                          <blockquote
                                                          class="gmail_quote"
                                                          style="margin:
                                                          0pt 0pt 0pt
                                                          0.8ex;
                                                          border-left:
                                                          1px solid
                                                          rgb(204, 204,
                                                          204);
                                                          padding-left:
                                                          1ex;">
                                                          <div
                                                          bgcolor="#ffffff"
                                                          text="#000000">
                                                          <div>
                                                          <div><br>
                                                          <br>
                                                          <blockquote
                                                          type="cite">
                                                          <div>
                                                          <div
                                                          class="gmail_quote">
                                                          <div><br>
                                                          </div>
                                                          <div>Hong</div>
                                                          <div><br>
                                                          </div>
                                                          <div> </div>
                                                          <blockquote
                                                          class="gmail_quote"
                                                          style="margin:
                                                          0pt 0pt 0pt
                                                          0.8ex;
                                                          border-left:
                                                          1px solid
                                                          rgb(204, 204,
                                                          204);
                                                          padding-left:
                                                          1ex;">
                                                          <div
                                                          bgcolor="#ffffff"
                                                          text="#000000">
                                                          C =
                                                          PetscBinaryRead('C.dat','complex',true);<br>
                                                          <br>
                                                          Matrix C is
                                                          different
                                                          depending on
                                                          number of
                                                          cores I use. <br>
                                                          My PETSc is:<br>
                                                          Using Petsc
                                                          Development HG
                                                          revision:
                                                          876c894d95f4fa6561d0a91310ca914592527960 
                                                          HG Date: Tue
                                                          Jan 10
                                                          19:27:14 2012
                                                          +0100
                                                          <div>
                                                          <div><br>
                                                          <br>
                                                          On 06.02.2012
                                                          17:13, Hong
                                                          Zhang wrote:
                                                          <blockquote
                                                          type="cite">MatMatMult()



                                                          in petsc is
                                                          not
                                                          well-tested
                                                          for complex -
                                                          could be
                                                          buggy.
                                                          <div>Can you
                                                          send us the
                                                          matrices A and
                                                          B in petsc
                                                          binary format
                                                          for
                                                          investigation?</div>
                                                          <div><br>
                                                          </div>
                                                          <div>Hong<br>
                                                          <br>
                                                          <div
                                                          class="gmail_quote">On



                                                          Mon, Feb 6,
                                                          2012 at 5:55
                                                          AM, Alexander
                                                          Grayver <span
                                                          dir="ltr"><<a
moz-do-not-send="true" href="mailto:agrayver@gfz-potsdam.de"
                                                          target="_blank">agrayver@gfz-potsdam.de</a>></span>
                                                          wrote:<br>
                                                          <blockquote
                                                          class="gmail_quote"
                                                          style="margin:
                                                          0pt 0pt 0pt
                                                          0.8ex;
                                                          border-left:
                                                          1px solid
                                                          rgb(204, 204,
                                                          204);
                                                          padding-left:
                                                          1ex;">Dear
                                                          PETSc team,<br>
                                                          <br>
                                                          I try to use:<br>
                                                          call
MatMatMult(A,B,MAT_INITIAL_MATRIX,PETSC_DEFAULT_DOUBLE_PRECISION,C,ierr);CHKERRQ(ierr)<br>
                                                          <br>
                                                          Where both A
                                                          and B are
                                                          rectangular,
                                                          but A is
                                                          sparse and B
                                                          is dense. Both
                                                          are double
                                                          complex and
                                                          distributed.<br>
                                                          The product
                                                          PETSc gives me
                                                          contains some
                                                          errors in some
                                                          part of the
                                                          matrix.<br>
                                                          I output A, B
                                                          and C then
                                                          computed
                                                          product in
                                                          matlab.<br>
                                                          <br>
                                                          Attached you
                                                          see figure
                                                          plotted as:<br>
imagesc(log10(abs(C-Cm)))<br>
                                                          <br>
                                                          Where Cm --
                                                          product
                                                          computed in
                                                          matlab.<br>
                                                          <br>
                                                          The pattern
                                                          and amplitude
                                                          vary depending
                                                          on the number
                                                          of cores I
                                                          use. This
                                                          picture is
                                                          obtained for
                                                          48 cores (I've
                                                          tried 12, 64
                                                          cores as
                                                          well).<br>
                                                          <br>
                                                          Where should I
                                                          look for
                                                          possible
                                                          explanation?<span><font
color="#888888"><br>
                                                          <br>
                                                          -- <br>
                                                          Regards,<br>
                                                          Alexander<br>
                                                          </font></span></blockquote>
                                                          </div>
                                                          <br>
                                                          </div>
                                                          </blockquote>
                                                          <br>
                                                          <br>
                                                          </div>
                                                          </div>
                                                          <span><font
                                                          color="#888888">
                                                          <pre cols="72">-- 
Regards,
Alexander</pre>
                                                          </font></span></div>
                                                          </blockquote>
                                                          </div>
                                                          <br>
                                                          </div>
                                                          </blockquote>
                                                          <br>
                                                          <br>
                                                          </div>
                                                          </div>
                                                          <span><font
                                                          color="#888888">
                                                          <pre cols="72">-- 
Regards,
Alexander</pre>
                                                          </font></span></div>
                                                          </blockquote>
                                                          </div>
                                                          <br>
                                                        </blockquote>
                                                        <br>
                                                        <br>
                                                      </div>
                                                    </div>
                                                    <span><font
                                                        color="#888888">
                                                        <pre cols="72">-- 
Regards,
Alexander</pre>
                                                      </font></span></div>
                                                </blockquote>
                                              </div>
                                              <br>
                                            </div>
                                          </div>
                                        </blockquote>
                                      </div>
                                      <br>
                                    </div>
                                  </blockquote>
                                  <br>
                                  <br>
                                </div>
                              </div>
                              <span><font color="#888888">
                                  <pre cols="72">-- 
Regards,
Alexander</pre>
                                </font></span></div>
                          </blockquote>
                        </div>
                        <br>
                      </div>
                    </blockquote>
                    <br>
                    <br>
                  </div>
                </div>
                <span class="HOEnZb"><font color="#888888">
                    <pre cols="72">-- 
Regards,
Alexander</pre>
                  </font></span></div>
            </blockquote>
          </div>
          <br>
        </div>
      </blockquote>
      <br>
      <br>
      <pre class="moz-signature" cols="72">-- 
Regards,
Alexander</pre>
    </blockquote>
    <br>
    <br>
    <pre class="moz-signature" cols="72">-- 
Regards,
Alexander</pre>
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