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<p>Hi Jose, <br>
</p>
<p>Here is the part of the code:</p>
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<div> ierr = STSetType(st,STSINVERT);CHKERRQ(ierr);<br>
<br>
ierr = STGetKSP(st,&ksp);CHKERRQ(ierr);<br>
ierr = KSPSetType(ksp,KSPPREONLY);CHKERRQ(ierr);<br>
ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);<br>
ierr = PCSetType(pc,PCCHOLESKY);CHKERRQ(ierr);<br>
<br>
#if defined(PETSC_HAVE_MUMPS)<br>
#if defined(PETSC_USE_COMPLEX)<br>
SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Spectrum slicing with MUMPS is not available for complex scalars");<br>
#endif<br>
ierr = PetscPrintf(PETSC_COMM_WORLD, "PETSC_HAVE_MUMPS\n");CHKERRQ(ierr);<br>
ierr = EPSKrylovSchurSetDetectZeros(eps,PETSC_TRUE);CHKERRQ(ierr); /* enforce zero detection */<br>
ierr = PCFactorSetMatSolverPackage(pc,MATSOLVERMUMPS);CHKERRQ(ierr);<br>
/*<br>
Add several MUMPS options (currently there is no better way of setting this in program):<br>
'-mat_mumps_icntl_13 1': turn off ScaLAPACK for matrix inertia<br>
'-mat_mumps_icntl_24 1': detect null pivots in factorization (for the case that a shift is equal to an eigenvalue)<br>
'-mat_mumps_cntl_3 <tol>': a tolerance used for null pivot detection (must be larger than machine epsilon)<br>
<br>
Note: depending on the interval, it may be necessary also to increase the workspace:<br>
'-mat_mumps_icntl_14 <percentage>': increase workspace with a percentage (50, 100 or more)<br>
*/<br>
ierr = PetscOptionsInsertString(NULL,"-mat_mumps_icntl_13 1 -mat_mumps_icntl_24 1 -mat_mumps_cntl_3 1e-12");CHKERRQ(ierr);<br>
#endif<br>
<br>
/*<br>
Set solver parameters at runtime<br>
*/<br>
ierr = EPSSetFromOptions(eps);CHKERRQ(ierr);<br>
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<p></p>
<p><br>
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<p>I am using MUMPS. Actually it's the example I said before. I didn't modify it that much.</p>
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<p>M Hassan<br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Jose E. Roman <jroman@dsic.upv.es><br>
<b>Sent:</b> Sunday, July 24, 2016 1:27:04 PM<br>
<b>To:</b> Hassan Md Mahmudulla<br>
<b>Cc:</b> petsc-users@mcs.anl.gov<br>
<b>Subject:</b> Re: [petsc-users] EPSKrylovSchurSetDetectZeros() not working</font>
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> El 24 jul 2016, a las 19:50, Hassan Md Mahmudulla <mhassan@miners.utep.edu> escribió:<br>
> <br>
> Hi,<br>
> I am solving a generalized eigenvalue problem using spectrum slicing. I am using this example (<a href="http://slepc.upv.es/documentation/current/src/eps/examples/tutorials/ex25.c.html">http://slepc.upv.es/documentation/current/src/eps/examples/tutorials/ex25.c.html</a>)
as it is. Part of the code is:<br>
> ierr =EPSKrylovSchurSetDetectZeros(eps,PETSC_TRUE);CHKERRQ(ierr);<br>
> <br>
> But I am getting the following: <br>
> <br>
> [0]PETSC ERROR: Mismatch between number of values found and information from inertia, consider using EPSKrylovSchurSetDetectZeros()<br>
> [0]PETSC ERROR: See <a href="http://www.mcs.anl.gov/petsc/documentation/faq.html">
http://www.mcs.anl.gov/petsc/documentation/faq.html</a> for trouble shooting.<br>
> <br>
> It seems the input PETSC_TRUE is not working for EPSKrylovSchurSetDetectZeros(). Any idea?<br>
> <br>
> M Hassan<br>
<br>
It seems that you are not using MUMPS. Spectrum slicing can be used with PETSc's Cholesky, but for guaranteed robustness it is necessary to use MUMPS.<br>
<br>
Jose<br>
<br>
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