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<div id="version" align=right><b>slepc-3.23.1 2025-05-01</b></div>
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<H1>BVSetActiveColumns</H1>
Specify the columns that will be involved in operations.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepcbv.h"
<A HREF="https://petsc.org/release/manualpages/Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../BV/BVSetActiveColumns.html#BVSetActiveColumns">BVSetActiveColumns</A>(<A HREF="../BV/BV.html#BV">BV</A> bv,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> l,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> k)
</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>bv </B></TD><TD> - the basis vectors context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>l </B></TD><TD> - number of leading columns
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>k </B></TD><TD> - number of active columns
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
In operations such as <A HREF="../BV/BVMult.html#BVMult">BVMult</A>() or <A HREF="../BV/BVDot.html#BVDot">BVDot</A>(), only the first k columns are
considered. This is useful when the <A HREF="../BV/BV.html#BV">BV</A> is filled from left to right, so
the last m-k columns do not have relevant information.
<P>
Also in operations such as <A HREF="../BV/BVMult.html#BVMult">BVMult</A>() or <A HREF="../BV/BVDot.html#BVDot">BVDot</A>(), the first l columns are
normally not included in the computation. See the manpage of each
operation.
<P>
In orthogonalization operations, the first l columns are treated
differently, they participate in the orthogonalization but the computed
coefficients are not stored.
<P>
Use <A HREF="https://petsc.org/release/manualpages/Sys/PETSC_CURRENT.html#PETSC_CURRENT">PETSC_CURRENT</A> to leave any of the values unchanged. Use <A HREF="https://petsc.org/release/manualpages/Sys/PETSC_DETERMINE.html#PETSC_DETERMINE">PETSC_DETERMINE</A>
to set l to the minimum value (0) and k to the maximum (m).
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../BV/BVGetActiveColumns.html#BVGetActiveColumns">BVGetActiveColumns</A>(), <A HREF="../BV/BVSetSizes.html#BVSetSizes">BVSetSizes</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/sys/classes/bv/interface/bvbasic.c.html#BVSetActiveColumns">src/sys/classes/bv/interface/bvbasic.c</A>
<BR><BR><A HREF="./index.html">Index of all BV routines</A>
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