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<div id="version" align=right><b>petsc-3.10.3 2018-12-18</b></div>
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<A NAME="PCVPBJACOBI"><H1>PCVPBJACOBI</H1></A>
Variable size point block Jacobi preconditioner
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
See <A HREF="../PC/PCJACOBI.html#PCJACOBI">PCJACOBI</A> for point Jacobi preconditioning, <A HREF="../PC/PCPBJACOBI.html#PCPBJACOBI">PCPBJACOBI</A> for fixed point block size, and <A HREF="../PC/PCBJACOBI.html#PCBJACOBI">PCBJACOBI</A> for large size blocks
<P>
This works for AIJ matrices
<P>
Uses dense LU factorization with partial pivoting to invert the blocks; if a zero pivot
is detected a PETSc error is generated.
<P>
One must call <A HREF="../Mat/MatSetVariableBlockSizes.html#MatSetVariableBlockSizes">MatSetVariableBlockSizes</A>() to use this preconditioner
<H3><FONT COLOR="#CC3333">Developer Notes</FONT></H3>
This should support the <A HREF="../PC/PCSetErrorIfFailure.html#PCSetErrorIfFailure">PCSetErrorIfFailure</A>() flag set to <A HREF="../Sys/PETSC_TRUE.html#PETSC_TRUE">PETSC_TRUE</A> to allow
the factorization to continue even after a zero pivot is found resulting in a Nan and hence
terminating <A HREF="../KSP/KSP.html#KSP">KSP</A> with a KSP_DIVERGED_NANORIF allowing
a nonlinear solver/ODE integrator to recover without stopping the program as currently happens.
<P>
Perhaps should provide an option that allows generation of a valid preconditioner
even if a block is singular as the <A HREF="../PC/PCJACOBI.html#PCJACOBI">PCJACOBI</A> does.
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Mat/MatSetVariableBlockSizes.html#MatSetVariableBlockSizes">MatSetVariableBlockSizes</A>(), <A HREF="../PC/PCCreate.html#PCCreate">PCCreate</A>(), <A HREF="../PC/PCSetType.html#PCSetType">PCSetType</A>(), <A HREF="../PC/PCType.html#PCType">PCType</A> (for list of available types), <A HREF="../PC/PC.html#PC">PC</A>, <A HREF="../PC/PCJACOBI.html#PCJACOBI">PCJACOBI</A>
<BR>
<P>
<P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>beginner<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/ksp/pc/impls/vpbjacobi/vpbjacobi.c.html#PCVPBJACOBI">src/ksp/pc/impls/vpbjacobi/vpbjacobi.c</A>
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