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<H1>QEPSetInitialSpaceLeft</H1>
Specify a basis of vectors that constitute the initial left space, that is, the subspace from which the solver starts to iterate for building the left subspace (in methods that work with two subspaces).
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepcqep.h"
PetscErrorCode QEPSetInitialSpaceLeft(QEP qep,PetscInt n,Vec *is)
</PRE>
Collective on <A HREF="../QEP/QEP.html#QEP">QEP</A> and Vec
<P>
<H3><FONT COLOR="#883300">Input Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>qep </B></TD><TD> - the quadratic 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 left space
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
Some solvers start to iterate on a single vector (initial left vector). In that case,
the other vectors are ignored.
<P>
These vectors do not persist from one <A HREF="../QEP/QEPSolve.html#QEPSolve">QEPSolve</A>() call to the other, so the
initial left 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 left eigenspace. Then, convergence may be faster.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../QEP/QEPSetInitialSpace.html#QEPSetInitialSpace">QEPSetInitialSpace</A>()
<BR><P><B><FONT COLOR="#883300">Location: </FONT></B><A HREF="../../../src/qep/interface/qepsetup.c.html#QEPSetInitialSpaceLeft">src/qep/interface/qepsetup.c</A>
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