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<div id="version" align=right><b>slepc-3.22.2 2024-12-02</b></div>
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<H1>PEPSetInterval</H1>
Defines the computational interval for spectrum slicing.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepcpep.h"
<A HREF="https://petsc.org/release/manualpages/Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../PEP/PEPSetInterval.html#PEPSetInterval">PEPSetInterval</A>(<A HREF="../PEP/PEP.html#PEP">PEP</A> pep,<A HREF="https://petsc.org/release/manualpages/Sys/PetscReal.html#PetscReal">PetscReal</A> inta,<A HREF="https://petsc.org/release/manualpages/Sys/PetscReal.html#PetscReal">PetscReal</A> intb)
</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>pep </B></TD><TD> - eigensolver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>inta </B></TD><TD> - left end of the interval
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>intb </B></TD><TD> - right end of the interval
</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>-pep_interval <a,b> </B></TD><TD> - set [a,b] as the interval of interest
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
Spectrum slicing is a technique employed for computing all eigenvalues of
symmetric eigenproblems in a given interval. This function provides the
interval to be considered. It must be used in combination with <A HREF="../PEP/PEPWhich.html#PEPWhich">PEP_ALL</A>, see
<A HREF="../PEP/PEPSetWhichEigenpairs.html#PEPSetWhichEigenpairs">PEPSetWhichEigenpairs</A>().
<P>
In the command-line option, two values must be provided. For an open interval,
one can give an infinite, e.g., -pep_interval 1.0,inf or -pep_interval -inf,1.0.
An open interval in the programmatic interface can be specified with
<A HREF="https://petsc.org/release/manualpages/Sys/PETSC_MAX_REAL.html#PETSC_MAX_REAL">PETSC_MAX_REAL</A> and -<A HREF="https://petsc.org/release/manualpages/Sys/PETSC_MAX_REAL.html#PETSC_MAX_REAL">PETSC_MAX_REAL</A>.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../PEP/PEPGetInterval.html#PEPGetInterval">PEPGetInterval</A>(), <A HREF="../PEP/PEPSetWhichEigenpairs.html#PEPSetWhichEigenpairs">PEPSetWhichEigenpairs</A>()
<BR><P><B></B><H3><FONT COLOR="#883300">Level</FONT></H3>intermediate<BR>
<H3><FONT COLOR="#883300">Location</FONT></H3>
</B><A HREF="../../../src/pep/interface/pepbasic.c.html#PEPSetInterval">src/pep/interface/pepbasic.c</A>
<P><H3><FONT COLOR="#883300">Examples</FONT></H3>
<A HREF="../../../src/pep/tutorials/ex38.c.html">src/pep/tutorials/ex38.c</A><BR>
<A HREF="../../../src/pep/tutorials/ex40.c.html">src/pep/tutorials/ex40.c</A><BR>
<BR><BR><A HREF="./index.html">Index of all PEP routines</A>
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