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<br><div><div>Le 11 déc. 2014 à 11:43, Matthew Knepley <<a href="mailto:knepley@gmail.com">knepley@gmail.com</a>> a écrit :</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Thu, Dec 11, 2014 at 4:38 AM, Marc MEDALE <span dir="ltr"><<a href="mailto:marc.medale@univ-amu.fr" target="_blank">marc.medale@univ-amu.fr</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; position: static; z-index: auto; ">Dear PETSC Users,<br>
<br>
I have just updated to PETSc-3.5 my research code that uses PETSc for a while but I'm facing an astonishing difference between PETSc-3.4 to 3.5 versions when solving a very ill conditioned algebraic system with MUMPS (4.10.0 in both cases).<br>
<br>
The only differences that arise in my fortran source code are the following:<br>
Loma1-medale% diff ../version_3.5/solvEFL_MAN_SBIF.F ../version_3.4/solvEFL_MAN_SBIF.F<br>
336,337d335<br>
< CALL MatSetOption(MATGLOB,MAT_KEEP_NONZERO_PATTERN,<br>
< & PETSC_TRUE,IER)<br>
749,750c747,748<br>
< CALL KSPSetTolerances(KSP1,TOL,PETSC_DEFAULT_REAL,<br>
< & PETSC_DEFAULT_REAL,PETSC_DEFAULT_INTEGER,IER)<br>
---<br>
> CALL KSPSetTolerances(KSP1,TOL,PETSC_DEFAULT_DOUBLE_PRECISION,<br>
> & PETSC_DEFAULT_DOUBLE_PRECISION,PETSC_DEFAULT_INTEGER,IER)<br>
909c907,908<br>
< CALL KSPSetOperators(KSP1,MATGLOB,MATGLOB,IER)<br>
---<br>
> CALL KSPSetOperators(KSP1,MATGLOB,MATGLOB,<br>
> & SAME_NONZERO_PATTERN,IER)<br>
<br>
When I run the corresponding program versions on 128 cores of our cluster with the same input data and the following command line arguments:<br>
-ksp_type preonly -pc_type lu -pc_factor_mat_solver_package mumps -mat_mumps_icntl_8 0<br>
<br>
I get the following outputs:<br>
a) with PETSc-3.4p4:<br>
L2 norm of solution vector: 7.39640E-02,<br>
<br>
b) with PETSc-3.5p1:<br>
L2 norm of solution vector: 1.61325E-02<br>
<br>
Do I have change something else in updating my code based on KSP from PETSc-3.4 to 3.5 versions?<br>
Do any default values in the PETSc-MUMPS interface have been changed from PETSc-3.4 to 3.5?<br>
Any hints or suggestions are welcome to help me to recover the right results (obtained with PETSc-3.4).<br></blockquote><div><br></div><div>Send the output from -ksp_monitor -ksp_view for both runs. I am guessing that a MUMPS default changed between versions.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Thank you very much.<br>
<span class="HOEnZb"><font color="#888888"><br>
Marc MEDALE.</font></span></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>
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