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<div id="version" align=right><b>slepc-3.22.2 2024-12-02</b></div>
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<H1>EPSGetEigenpair</H1>
Gets the i-th solution of the eigenproblem as computed by <A HREF="../EPS/EPSSolve.html#EPSSolve">EPSSolve</A>(). The solution consists in both the eigenvalue and the eigenvector.
<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/EPSGetEigenpair.html#EPSGetEigenpair">EPSGetEigenpair</A>(<A HREF="../EPS/EPS.html#EPS">EPS</A> eps,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> i,<A HREF="https://petsc.org/release/manualpages/Sys/PetscScalar.html#PetscScalar">PetscScalar</A> *eigr,<A HREF="https://petsc.org/release/manualpages/Sys/PetscScalar.html#PetscScalar">PetscScalar</A> *eigi,<A HREF="https://petsc.org/release/manualpages/Vec/Vec.html#Vec">Vec</A> Vr,<A HREF="https://petsc.org/release/manualpages/Vec/Vec.html#Vec">Vec</A> Vi)
</PRE>
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> - eigensolver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>i </B></TD><TD> - index of the solution
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Output Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>eigr </B></TD><TD> - real part of eigenvalue
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>eigi </B></TD><TD> - imaginary part of eigenvalue
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>Vr </B></TD><TD> - real part of eigenvector
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>Vi </B></TD><TD> - imaginary part of eigenvector
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
It is allowed to pass NULL for Vr and Vi, if the eigenvector is not
required. Otherwise, the caller must provide valid <A HREF="https://petsc.org/release/manualpages/Vec/Vec.html#Vec">Vec</A> objects, i.e.,
they must be created by the calling program with e.g. <A HREF="https://petsc.org/release/manualpages/Mat/MatCreateVecs.html#MatCreateVecs">MatCreateVecs</A>().
<P>
If the eigenvalue is real, then eigi and Vi are set to zero. If PETSc is
configured with complex scalars the eigenvalue is stored
directly in eigr (eigi is set to zero) and the eigenvector in Vr (Vi is
set to zero). In both cases, the user can pass NULL in eigi and Vi.
<P>
The index i should be a value between 0 and nconv-1 (see <A HREF="../EPS/EPSGetConverged.html#EPSGetConverged">EPSGetConverged</A>()).
Eigenpairs are indexed according to the ordering criterion established
with <A HREF="../EPS/EPSSetWhichEigenpairs.html#EPSSetWhichEigenpairs">EPSSetWhichEigenpairs</A>().
<P>
The 2-norm of the eigenvector is one unless the problem is generalized
Hermitian. In this case the eigenvector is normalized with respect to the
norm defined by the B matrix.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../EPS/EPSGetEigenvalue.html#EPSGetEigenvalue">EPSGetEigenvalue</A>(), <A HREF="../EPS/EPSGetEigenvector.html#EPSGetEigenvector">EPSGetEigenvector</A>(), <A HREF="../EPS/EPSGetLeftEigenvector.html#EPSGetLeftEigenvector">EPSGetLeftEigenvector</A>(), <A HREF="../EPS/EPSSolve.html#EPSSolve">EPSSolve</A>(),
<BR><A HREF="../EPS/EPSGetConverged.html#EPSGetConverged">EPSGetConverged</A>(), <A HREF="../EPS/EPSSetWhichEigenpairs.html#EPSSetWhichEigenpairs">EPSSetWhichEigenpairs</A>(), <A HREF="../EPS/EPSGetInvariantSubspace.html#EPSGetInvariantSubspace">EPSGetInvariantSubspace</A>()
<P><B></B><H3><FONT COLOR="#883300">Level</FONT></H3>beginner<BR>
<H3><FONT COLOR="#883300">Location</FONT></H3>
</B><A HREF="../../../src/eps/interface/epssolve.c.html#EPSGetEigenpair">src/eps/interface/epssolve.c</A>
<P><H3><FONT COLOR="#883300">Examples</FONT></H3>
<A HREF="../../../src/eps/tutorials/ex1.c.html">src/eps/tutorials/ex1.c</A><BR>
<A HREF="../../../src/eps/tutorials/ex19.c.html">src/eps/tutorials/ex19.c</A><BR>
<A HREF="../../../src/eps/tutorials/ex24.c.html">src/eps/tutorials/ex24.c</A><BR>
<A HREF="../../../src/eps/tutorials/ex31.c.html">src/eps/tutorials/ex31.c</A><BR>
<A HREF="../../../src/eps/tutorials/ex34.c.html">src/eps/tutorials/ex34.c</A><BR>
<A HREF="../../../src/eps/tutorials/ex41.c.html">src/eps/tutorials/ex41.c</A><BR>
<BR><BR><A HREF="./index.html">Index of all EPS routines</A>
<BR><A HREF="../../../docs/manual.html">Table of Contents for all manual pages</A>
<BR><A HREF="../singleindex.html">Index of all manual pages</A>
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