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    <div class="moz-cite-prefix">But I need to setup the boundary
      conditions for the solution vector X, which is in
      FormMassTimeStep(). <br>
      <br>
      Best regards,<br>
      Rongliang<br>
      <br>
      <br>
      On 04/02/2016 08:37 PM, Matthew Knepley wrote:<br>
    </div>
    <blockquote
cite="mid:CAMYG4Gk57vXcB79z-JkLO9rgx_Qv0G7wQ+_icQEgag29BkvSJw@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div class="gmail_extra">
          <div class="gmail_quote">On Sat, Apr 2, 2016 at 7:37 AM,
            Rongliang Chen <span dir="ltr"><<a
                moz-do-not-send="true" href="mailto:rl.chen@siat.ac.cn"
                target="_blank">rl.chen@siat.ac.cn</a>></span> wrote:<br>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
              <div bgcolor="#FFFFFF" text="#000000">
                <div>Hi Matt,<br>
                  <br>
                  How to check in the explicit method? This kind of
                  errors does come out in the explicit method. <br>
                </div>
              </div>
            </blockquote>
            <div><br>
            </div>
            <div>You said "that is I use the explicit method with the
              same function FormMassTimeStep(), this error disappeared"</div>
            <div> </div>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
              <div bgcolor="#FFFFFF" text="#000000">
                <div> What do you mean "You should never be changing the
                  input guess"? Do you mean that the value of the
                  solution vector X in FormFunction are not allowed to
                  be changed by the user defined function?<br>
                </div>
              </div>
            </blockquote>
            <div><br>
            </div>
            <div>Yes.</div>
            <div><br>
            </div>
            <div>   Matt</div>
            <div> </div>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
              <div bgcolor="#FFFFFF" text="#000000">
                <div> Best regards,<br>
                  Rongliang<br>
                  <br>
                  On 04/02/2016 08:19 PM, Matthew Knepley wrote:<br>
                </div>
                <blockquote type="cite">
                  <div dir="ltr">
                    <div class="gmail_extra">
                      <div class="gmail_quote">On Sat, Apr 2, 2016 at
                        7:15 AM, Rongliang Chen <span dir="ltr"><<a
                            moz-do-not-send="true"
                            href="mailto:rl.chen@siat.ac.cn"
                            target="_blank">rl.chen@siat.ac.cn</a>></span>
                        wrote:<br>
                        <blockquote class="gmail_quote"
                          style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
                          <div bgcolor="#FFFFFF" text="#000000">
                            <div>Hi Matt,<br>
                              <br>
                              That's right. The FormMassTimeStep() is
                              inside the FormFunction() and I call the
                              FormFunction() in this way:
                              SNESSetFunction(user->snes,
                              algebra->f, FormFunction, (void*)user).
                              How can I know the X is read-only or not?
                              <br>
                            </div>
                          </div>
                        </blockquote>
                        <div><br>
                        </div>
                        <div>Exactly that you get this error message,
                          and it should be in the documentation.</div>
                        <div> </div>
                        <blockquote class="gmail_quote"
                          style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
                          <div bgcolor="#FFFFFF" text="#000000">
                            <div> If I do not use the SNESSolve, that is
                              I use the explicit method with the same
                              function FormMassTimeStep(), this error
                              disappeared. So it seems that the
                              SNESSolve locked the vector X. <br>
                            </div>
                          </div>
                        </blockquote>
                        <div><br>
                        </div>
                        <div>Then we need to put that check in the
                          explicit method as well. You should never be
                          changing the input guess.</div>
                        <div><br>
                        </div>
                        <div>  Thanks,</div>
                        <div><br>
                        </div>
                        <div>    Matt</div>
                        <div> </div>
                        <blockquote class="gmail_quote"
                          style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
                          <div bgcolor="#FFFFFF" text="#000000">
                            <div> Best regards,<br>
                              Rongliang<br>
                              <br>
                              On 04/02/2016 07:59 PM, Matthew Knepley
                              wrote:<br>
                            </div>
                            <blockquote type="cite">
                              <div dir="ltr">
                                <div class="gmail_extra">
                                  <div class="gmail_quote">On Sat, Apr
                                    2, 2016 at 6:49 AM, Rongliang Chen <span
                                      dir="ltr"><<a
                                        moz-do-not-send="true"
                                        href="mailto:rl.chen@siat.ac.cn"
                                        target="_blank">rl.chen@siat.ac.cn</a>></span>
                                    wrote:<br>
                                    <blockquote class="gmail_quote"
                                      style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
                                      <div bgcolor="#FFFFFF"
                                        text="#000000">
                                        <div>Hi Dave,<br>
                                          <br>
                                          I did not call any
                                          VecGetArrary and
                                          VecGetArraryRead in function
                                          FormMassTimeStepFunction().<br>
                                        </div>
                                      </div>
                                    </blockquote>
                                    <div><br>
                                    </div>
                                    <div>It looks like you have a
                                      function FormMassTimeStep() inside
                                      your FormFunction() method. This</div>
                                    <div>has an argument X, the solution
                                      guess, which is read-only.
                                      However, you are calling
                                      DMLocalToGlobal()</div>
                                    <div>using that X, which is illegal,
                                      since its read-only. Is this
                                      right?</div>
                                    <div><br>
                                    </div>
                                    <div>   Matt</div>
                                    <div> </div>
                                    <blockquote class="gmail_quote"
                                      style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
                                      <div bgcolor="#FFFFFF"
                                        text="#000000">
                                        <div> Best regards,<br>
                                          Rongliang<br>
                                          <br>
                                          On 04/02/2016 06:20 PM, Dave
                                          May wrote:<br>
                                        </div>
                                        <blockquote type="cite">
                                          <div dir="ltr"><br>
                                            <div class="gmail_extra"><br>
                                              <div class="gmail_quote">On
                                                2 April 2016 at 11:18,
                                                Rongliang Chen <span
                                                  dir="ltr"><<a
                                                    moz-do-not-send="true"
href="mailto:rl.chen@siat.ac.cn" target="_blank">rl.chen@siat.ac.cn</a>></span>
                                                wrote:<br>
                                                <blockquote
                                                  class="gmail_quote"
                                                  style="margin:0px 0px
                                                  0px
0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">Hi

                                                  Shri,<br>
                                                  <br>
                                                  Thanks for your reply.<br>
                                                  <br>
                                                  Do you mean that I
                                                  need to change the
                                                  VecGetArrary() in
                                                  /home/rlchen/soft/petsc-3.6.3/src/dm/interface/dm.c
                                                  to VecGetArrayRead()?<br>
                                                </blockquote>
                                                <div><br>
                                                </div>
                                                <div>No - you should
                                                  change it in your
                                                  function
                                                  FormMassTimeStepFunction().<br>
                                                </div>
                                                <div>The input vector x
                                                  passed into
                                                  SNESComputeFunction()
                                                  is read only.<br>
                                                </div>
                                                <div> <br>
                                                  <br>
                                                </div>
                                                <blockquote
                                                  class="gmail_quote"
                                                  style="margin:0px 0px
                                                  0px
0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">
                                                  <br>
                                                  I tried it and I got a
                                                  warning when I make
                                                  the petsc:<br>
                                                  <br>
                                                  /home/rlchen/soft/petsc-3.6.3/src/dm/interface/dm.c:


                                                  In function
                                                  ‘DMLocalToGlobalBegin’:<br>
                                                  /home/rlchen/soft/petsc-3.6.3/src/dm/interface/dm.c:1913:5:



                                                  warning: passing
                                                  argument 2 of
                                                  ‘VecGetArrayRead’ from
                                                  incompatible pointer
                                                  type [enabled by
                                                  default]<br>
                                                  In file included from
/home/rlchen/soft/petsc-3.6.3/include/petscmat.h:6:0,<br>
                                                  from
                                                  /home/rlchen/soft/petsc-3.6.3/include/petscdm.h:6,<br>
                                                  from
                                                  /home/rlchen/soft/petsc-3.6.3/include/petsc/private/dmimpl.h:6,<br>
                                                  from
                                                  /home/rlchen/soft/petsc-3.6.3/src/dm/interface/dm.c:1:<br>
                                                  /home/rlchen/soft/petsc-3.6.3/include/petscvec.h:420:29:



                                                  note: expected ‘const
                                                  PetscScalar **’ but
                                                  argument is of type
                                                  ‘PetscScalar **’<br>
                                                  <br>
                                                  Best regards,<br>
                                                  Rongliang<br>
                                                  <br>
                                                  ---------------------<br>
                                                  Rongliang Chen,   PhD<br>
                                                  Associate Professor<br>
                                                  <br>
                                                  Laboratory for
                                                  Engineering and
                                                  Scientific Computing<br>
                                                  Shenzhen Institutes of
                                                  Advanced Technology<br>
                                                  Chinese Academy of
                                                  Sciences<br>
                                                  Address: 1068 Xueyuan
                                                  Avenue, Shenzhen
                                                  University Town,
                                                  Shenzhen, Guangdong
                                                  (518055), P. R. China<br>
                                                  E-mail:  <a
                                                    moz-do-not-send="true"
href="mailto:rl.chen@siat.ac.cn" target="_blank">rl.chen@siat.ac.cn</a><br>
                                                  Phone: <a
                                                    moz-do-not-send="true"
href="tel:%2B86-755-86392312" value="+8675586392312" target="_blank">+86-755-86392312</a>
                                                  <div>
                                                    <div><br>
                                                      <br>
                                                      On 04/02/2016
                                                      05:03 PM,
                                                      Abhyankar,
                                                      Shrirang G. wrote:<br>
                                                      <blockquote
                                                        class="gmail_quote"
                                                        style="margin:0px
                                                        0px 0px
0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">
                                                        Use
                                                        VecGetArrayRead
                                                        instead of
                                                        VecGetArray<br>
                                                        <br>
                                                        <a
                                                          moz-do-not-send="true"
href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/VecGetArray"
rel="noreferrer" target="_blank">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/VecGetArray</a><br>
                                                        Read.html<br>
                                                        <br>
                                                        <br>
                                                        Shri<br>
                                                        <br>
                                                        -----Original
                                                        Message-----<br>
                                                        From: Rongliang
                                                        Chen <<a
                                                          moz-do-not-send="true"
href="mailto:rl.chen@siat.ac.cn" target="_blank">rl.chen@siat.ac.cn</a>><br>
                                                        Date: Saturday,
                                                        April 2, 2016 at
                                                        3:51 AM<br>
                                                        To: PETSc users
                                                        list <<a
                                                          moz-do-not-send="true"
href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>>,


                                                        "<a
                                                          moz-do-not-send="true"
href="mailto:rongliang.chan@gmail.com" target="_blank">rongliang.chan@gmail.com</a>"<br>
                                                        <<a
                                                          moz-do-not-send="true"
href="mailto:rongliang.chan@gmail.com" target="_blank">rongliang.chan@gmail.com</a>><br>
                                                        Subject:
                                                        [petsc-users]
                                                        Vec is locked
                                                        read only<br>
                                                        <br>
                                                        <blockquote
                                                          class="gmail_quote"
                                                          style="margin:0px
                                                          0px 0px
0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">
                                                          Dear All,<br>
                                                          <br>
                                                          My code got
                                                          the following
                                                          error
                                                          messages, but
                                                          the code works
                                                          well for<br>
                                                          the petsc
                                                          optimized
                                                          version
                                                          (--with-debugging=0).
                                                          Anyone can
                                                          tell me how<br>
                                                          to fix this
                                                          problem?<br>
                                                          <br>
                                                          Best regards,<br>
                                                          Rongliang<br>
                                                          <br>
                                                          <br>
                                                          [0]PETSC
                                                          ERROR:
                                                          ---------------------
                                                          Error Message<br>
--------------------------------------------------------------<br>
                                                          [0]PETSC
                                                          ERROR: Object
                                                          is in wrong
                                                          state<br>
                                                          [0]PETSC
                                                          ERROR:  Vec is
                                                          locked read
                                                          only, argument
                                                          # 1<br>
                                                          [0]PETSC
                                                          ERROR: See <a
moz-do-not-send="true"
                                                          href="http://www.mcs.anl.gov/petsc/documentation/faq.html"
rel="noreferrer" target="_blank">http://www.mcs.anl.gov/petsc/documentation/faq.html</a><br>
                                                          for trouble
                                                          shooting.<br>
                                                          [0]PETSC
                                                          ERROR: Petsc
                                                          Release
                                                          Version 3.6.3,
                                                          Dec, 03, 2015<br>
                                                          [0]PETSC
                                                          ERROR: ./Nwtun
                                                          on a
                                                          64bit-debug
                                                          named rlchen
                                                          by rlchen Sat
                                                          Apr<br>
                                                          2 15:40:32
                                                          2016<br>
                                                          [0]PETSC
                                                          ERROR:
                                                          Configure
                                                          options
                                                          --download-blacs
--download-scalapack<br>
                                                          --download-metis

                                                          --download-parmetis

--download-exodusii<br>
                                                          --download-netcdf

--download-hdf5<br>
--with-mpi-dir=/home/rlchen/soft/Program/mpich2-shared<br>
                                                          --with-debugging=1

                                                          --download-fblaslapack

--download-chaco<br>
                                                          [0]PETSC
                                                          ERROR: #1
                                                          VecGetArray()
                                                          line 1646 in<br>
/home/rlchen/soft/petsc-3.6.3/src/vec/vec/interface/rvector.c<br>
                                                          [0]PETSC
                                                          ERROR: #2
                                                          DMLocalToGlobalBegin()
                                                          line 1913 in<br>
/home/rlchen/soft/petsc-3.6.3/src/dm/interface/dm.c<br>
                                                          [0]PETSC
                                                          ERROR: #3
                                                          FormMassTimeStepFunction()
                                                          line 191 in<br>
/home/rlchen/soft/3D_fluid/FiniteVolumeMethod/PETScCodes/codefor3.6/SetupF<br>
                                                          unctions.c<br>
                                                          [0]PETSC
                                                          ERROR: #4
                                                          FormFunction()
                                                          line 46 in<br>
/home/rlchen/soft/3D_fluid/FiniteVolumeMethod/PETScCodes/codefor3.6/SetupF<br>
                                                          unctions.c<br>
                                                          [0]PETSC
                                                          ERROR: #5
                                                          SNESComputeFunction()
                                                          line 2067 in<br>
/home/rlchen/soft/petsc-3.6.3/src/snes/interface/snes.c<br>
                                                          [0]PETSC
                                                          ERROR: #6
                                                          SNESSolve_NEWTONLS()
                                                          line 184 in<br>
/home/rlchen/soft/petsc-3.6.3/src/snes/impls/ls/ls.c<br>
                                                          [0]PETSC
                                                          ERROR: #7
                                                          SNESSolve()
                                                          line 3906 in<br>
/home/rlchen/soft/petsc-3.6.3/src/snes/interface/snes.c<br>
                                                          [0]PETSC
                                                          ERROR: #8
                                                          SolveTimeDependent()
                                                          line 843 in<br>
/home/rlchen/soft/3D_fluid/FiniteVolumeMethod/PETScCodes/codefor3.6/Nwtun.<br>
                                                          c<br>
                                                          [0]PETSC
                                                          ERROR: #9
                                                          main() line
                                                          452 in<br>
/home/rlchen/soft/3D_fluid/FiniteVolumeMethod/PETScCodes/codefor3.6/Nwtun.<br>
                                                          c<br>
                                                          <br>
                                                          <br>
                                                        </blockquote>
                                                        <br>
                                                      </blockquote>
                                                      <br>
                                                      <br>
                                                    </div>
                                                  </div>
                                                </blockquote>
                                              </div>
                                              <br>
                                            </div>
                                          </div>
                                        </blockquote>
                                        <br>
                                      </div>
                                    </blockquote>
                                  </div>
                                  <br>
                                  <br clear="all">
                                  <span class=""><font color="#888888">
                                      <span><font color="#888888">
                                          <div><br>
                                          </div>
                                          -- <br>
                                          <div>What most experimenters
                                            take for granted before they
                                            begin their experiments is
                                            infinitely more interesting
                                            than any results to which
                                            their experiments lead.<br>
                                            -- Norbert Wiener</div>
                                        </font></span></font></span></div>
                                <span class=""><font color="#888888"> </font></span></div>
                              <span class=""><font color="#888888"> </font></span></blockquote>
                            <span class=""><font color="#888888"> <br>
                              </font></span></div>
                          <span class=""><font color="#888888"> </font></span></blockquote>
                        <span class=""><font color="#888888"> </font></span></div>
                      <span class=""><font color="#888888"> <br>
                          <br clear="all">
                          <div><br>
                          </div>
                          -- <br>
                          <div>What most experimenters take for granted
                            before they begin their experiments is
                            infinitely more interesting than any results
                            to which their experiments lead.<br>
                            -- Norbert Wiener</div>
                        </font></span></div>
                  </div>
                </blockquote>
                <br>
              </div>
            </blockquote>
          </div>
          <br>
          <br clear="all">
          <div><br>
          </div>
          -- <br>
          <div class="gmail_signature">What most experimenters take for
            granted before they begin their experiments is infinitely
            more interesting than any results to which their experiments
            lead.<br>
            -- Norbert Wiener</div>
        </div>
      </div>
    </blockquote>
    <br>
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