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<H1>EPSSetBalance</H1>
Specifies the balancing technique to be employed by the eigensolver, and some parameters associated to it.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepceps.h"
PetscErrorCode EPSSetBalance(EPS eps,EPSBalance bal,PetscInt its,PetscReal cutoff)
</PRE>
Logically Collective on <A HREF="../EPS/EPS.html#EPS">EPS</A>
<P>
<H3><FONT COLOR="#883300">Input Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>eps </B></TD><TD> - the eigensolver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>bal </B></TD><TD> - the balancing method, one of EPS_BALANCE_NONE, EPS_BALANCE_ONESIDE,
EPS_BALANCE_TWOSIDE, or EPS_BALANCE_USER
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>its </B></TD><TD> - number of iterations of the balancing algorithm
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>cutoff </B></TD><TD> - cutoff value
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Options Database Keys</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_balance <method> </B></TD><TD> - the balancing method, where <method> is one of
'none', 'oneside', 'twoside', or 'user'
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_balance_its <its> </B></TD><TD> - number of iterations
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_balance_cutoff <cutoff> </B></TD><TD> - cutoff value
</TD></TR></TABLE>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
When balancing is enabled, the solver works implicitly with matrix DAD^-1,
where D is an appropriate diagonal matrix. This improves the accuracy of
the computed results in some cases. See the SLEPc Users Manual for details.
<P>
Balancing makes sense only for non-Hermitian problems when the required
precision is high (i.e. a small tolerance such as 1e-15).
<P>
By default, balancing is disabled. The two-sided method is much more
effective than the one-sided counterpart, but it requires the system
matrices to have the MatMultTranspose operation defined.
<P>
The parameter 'its' is the number of iterations performed by the method. The
cutoff value is used only in the two-side variant. Use PETSC_IGNORE for an
argument that need not be changed. Use PETSC_DECIDE to assign a reasonably
good value.
<P>
User-defined balancing is allowed provided that the corresponding matrix
is set via <A HREF="../ST/STSetBalanceMatrix.html#STSetBalanceMatrix">STSetBalanceMatrix</A>.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../EPS/EPSGetBalance.html#EPSGetBalance">EPSGetBalance</A>(), <A HREF="../EPS/EPSBalance.html#EPSBalance">EPSBalance</A>, <A HREF="../ST/STSetBalanceMatrix.html#STSetBalanceMatrix">STSetBalanceMatrix</A>()
<BR><P><B><FONT COLOR="#883300">Location: </FONT></B><A HREF="../../../src/eps/interface/opts.c.html#EPSSetBalance">src/eps/interface/opts.c</A>
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