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<div id="version" align=right><b>slepc-3.23.1 2025-05-01</b></div>
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<H1>NEPSetInitialSpace</H1>
Specify a basis of vectors that constitute the initial space, that is, the subspace from which the solver starts to iterate.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepcnep.h"
<A HREF="https://petsc.org/release/manualpages/Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../NEP/NEPSetInitialSpace.html#NEPSetInitialSpace">NEPSetInitialSpace</A>(<A HREF="../NEP/NEP.html#NEP">NEP</A> nep,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> n,<A HREF="https://petsc.org/release/manualpages/Vec/Vec.html#Vec">Vec</A> is[])
</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>nep </B></TD><TD> - the nonlinear eigensolver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>n </B></TD><TD> - number of vectors
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>is </B></TD><TD> - set of basis vectors of the initial space
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
Some solvers start to iterate on a single vector (initial vector). In that case,
the other vectors are ignored.
<P>
These vectors do not persist from one <A HREF="../NEP/NEPSolve.html#NEPSolve">NEPSolve</A>() call to the other, so the
initial space should be set every time.
<P>
The vectors do not need to be mutually orthonormal, since they are explicitly
orthonormalized internally.
<P>
Common usage of this function is when the user can provide a rough approximation
of the wanted eigenspace. Then, convergence may be faster.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../NEP/NEPSetUp.html#NEPSetUp">NEPSetUp</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/nep/interface/nepsetup.c.html#NEPSetInitialSpace">src/nep/interface/nepsetup.c</A>
<P><H3><FONT COLOR="#883300">Examples</FONT></H3>
<A HREF="../../../src/nep/tutorials/ex20.c.html">src/nep/tutorials/ex20.c</A><BR>
<A HREF="../../../src/nep/tutorials/ex20f.F90.html">src/nep/tutorials/ex20f.F90</A><BR>
<BR><BR><A HREF="./index.html">Index of all NEP routines</A>
<BR><A HREF="../../../docs/manual.html">Table of Contents for all manual pages</A>
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