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<A NAME="PCCholeskySetShift"><H1>PCCholeskySetShift</H1></A>
specify whether to use Manteuffel shifting of Cholesky. If an Cholesky factorisation breaks down because of nonpositive pivots, adding sufficient identity to the diagonal will remedy this. Setting this causes a bisection method to find the minimum shift that will lead to a well-defined Cholesky.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscpc.h"
int PCCholeskySetShift(PC pc,PetscTruth shift)
</PRE>
<H3><FONT COLOR="#CC3333">Input parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>pc </B></TD><TD>- the preconditioner context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>shifting </B></TD><TD>- PETSC_TRUE to set shift else PETSC_FALSE
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database Key</FONT></H3>
<DT><B>-pc_ilu_shift </B> -Activate <A HREF="../PC/PCCholeskySetShift.html#PCCholeskySetShift">PCCholeskySetShift</A>()
<br>
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../PC/PC.html#PC">PC</A>, indefinite, factorization, incomplete, Cholesky
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../PC/PCILUSetShift.html#PCILUSetShift">PCILUSetShift</A>()
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>intermediate
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/pc/impls/cholesky/cholesky.c.html#PCCholeskySetShift">src/ksp/pc/impls/cholesky/cholesky.c</A>
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