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<div id="version" align=right><b>slepc-3.23.1 2025-05-01</b></div>
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<H1>EPSPowerSetShiftType</H1>
Sets the type of shifts used during the power iteration. This can be used to emulate the Rayleigh Quotient Iteration (RQI) method.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepceps.h"
<A HREF="https://petsc.org/release/manualpages/Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../EPS/EPSPowerSetShiftType.html#EPSPowerSetShiftType">EPSPowerSetShiftType</A>(<A HREF="../EPS/EPS.html#EPS">EPS</A> eps,<A HREF="../EPS/EPSPowerShiftType.html#EPSPowerShiftType">EPSPowerShiftType</A> shift)
</PRE>
Logically Collective
<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 eigenproblem solver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>shift </B></TD><TD> - the type of shift
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Options Database Key</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_power_shift_type </B></TD><TD> - Sets the shift type (either 'constant' or
'rayleigh' or 'wilkinson')
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
By default, shifts are constant (<A HREF="../EPS/EPSPowerShiftType.html#EPSPowerShiftType">EPS_POWER_SHIFT_CONSTANT</A>) and the iteration
is the simple power method (or inverse iteration if a shift-and-invert
transformation is being used).
<P>
A variable shift can be specified (<A HREF="../EPS/EPSPowerShiftType.html#EPSPowerShiftType">EPS_POWER_SHIFT_RAYLEIGH</A> or
<A HREF="../EPS/EPSPowerShiftType.html#EPSPowerShiftType">EPS_POWER_SHIFT_WILKINSON</A>). In this case, the iteration behaves rather like
a cubic converging method such as RQI.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../EPS/EPSPowerGetShiftType.html#EPSPowerGetShiftType">EPSPowerGetShiftType</A>(), <A HREF="../ST/STSetShift.html#STSetShift">STSetShift</A>(), <A HREF="../EPS/EPSPowerShiftType.html#EPSPowerShiftType">EPSPowerShiftType</A>
<BR><P><B></B><H3><FONT COLOR="#883300">Level</FONT></H3>advanced<BR>
<H3><FONT COLOR="#883300">Location</FONT></H3>
</B><A HREF="../../../src/eps/impls/power/power.c.html#EPSPowerSetShiftType">src/eps/impls/power/power.c</A>
<BR><BR><A HREF="./index.html">Index of all EPS routines</A>
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