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<div id="version" align=right><b>petsc-3.14.5 2021-03-03</b></div>
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<A NAME="PCFactorSetDropTolerance"><H1>PCFactorSetDropTolerance</H1></A>
The preconditioner will use an ILU based on a drop tolerance. (Under development)
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscpc.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../PC/PCFactorSetDropTolerance.html#PCFactorSetDropTolerance">PCFactorSetDropTolerance</A>(<A HREF="../PC/PC.html#PC">PC</A> pc,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> dt,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> dtcol,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> maxrowcount)
</PRE>
Logically Collective on <A HREF="../PC/PC.html#PC">PC</A>
<P>
<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>dt </B></TD><TD>- the drop tolerance, try from 1.e-10 to .1
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>dtcol </B></TD><TD>- tolerance for column pivot, good values [0.1 to 0.01]
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>maxrowcount </B></TD><TD>- the max number of nonzeros allowed in a row, best value
depends on the number of nonzeros in row of original matrix
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database Key</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_factor_drop_tolerance <dt,dtcol,maxrowcount> </B></TD><TD>- Sets drop tolerance
</TD></TR></TABLE>
<P>
<P>
There are NO default values for the 3 parameters, you must set them with reasonable values for your
matrix. We don't know how to compute reasonable values.
<P>
<P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>intermediate<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/ksp/pc/impls/factor/factor.c.html#PCFactorSetDropTolerance">src/ksp/pc/impls/factor/factor.c</A>
<P><H3><FONT COLOR="CC3333">Implementations</FONT></H3><A HREF="../../../src/ksp/pc/impls/factor/factimpl.c.html#PCFactorSetDropTolerance_Factor">PCFactorSetDropTolerance_Factor in src/ksp/pc/impls/factor/factimpl.c</A><BR>
<A HREF="../../../src/ksp/pc/impls/factor/ilu/ilu.c.html#PCFactorSetDropTolerance_ILU">PCFactorSetDropTolerance_ILU in src/ksp/pc/impls/factor/ilu/ilu.c</A><BR>
<BR><A HREF="./index.html">Index of all PC routines</A>
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