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<div id="version" align=right><b>slepc-3.23.1 2025-05-01</b></div>
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<H1>BVSetOrthogonalization</H1>
Specifies the method used for the orthogonalization of vectors (classical or modified Gram-Schmidt with or without refinement), and for the block-orthogonalization (simultaneous orthogonalization of a set of vectors).
<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/BVSetOrthogonalization.html#BVSetOrthogonalization">BVSetOrthogonalization</A>(<A HREF="../BV/BV.html#BV">BV</A> bv,<A HREF="../BV/BVOrthogType.html#BVOrthogType">BVOrthogType</A> type,<A HREF="../BV/BVOrthogRefineType.html#BVOrthogRefineType">BVOrthogRefineType</A> refine,<A HREF="https://petsc.org/release/manualpages/Sys/PetscReal.html#PetscReal">PetscReal</A> eta,<A HREF="../BV/BVOrthogBlockType.html#BVOrthogBlockType">BVOrthogBlockType</A> block)
</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>type </B></TD><TD> - the method of vector orthogonalization
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>refine </B></TD><TD> - type of refinement
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>eta </B></TD><TD> - parameter for selective refinement
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>block </B></TD><TD> - the method of block orthogonalization
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Options Database Keys</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-bv_orthog_type <type> </B></TD><TD> - Where <type> is cgs for Classical Gram-Schmidt orthogonalization
(default) or mgs for Modified Gram-Schmidt orthogonalization
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-bv_orthog_refine <ref> </B></TD><TD> - Where <ref> is one of never, ifneeded (default) or always
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-bv_orthog_eta <eta> </B></TD><TD> - For setting the value of eta
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-bv_orthog_block <block> </B></TD><TD> - Where <block> is the block-orthogonalization method
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
The default settings work well for most problems.
<P>
The parameter eta should be a real value between 0 and 1, that is used only when
the refinement type is "ifneeded". Use <A HREF="https://petsc.org/release/manualpages/Sys/PETSC_DETERMINE.html#PETSC_DETERMINE">PETSC_DETERMINE</A> to set a reasonable
default value. Use <A HREF="https://petsc.org/release/manualpages/Sys/PETSC_CURRENT.html#PETSC_CURRENT">PETSC_CURRENT</A> to leave the current value unchanged.
<P>
When using several processors, MGS is likely to result in bad scalability.
<P>
If the method set for block orthogonalization is GS, then the computation
is done column by column with the vector orthogonalization.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../BV/BVOrthogonalizeColumn.html#BVOrthogonalizeColumn">BVOrthogonalizeColumn</A>(), <A HREF="../BV/BVGetOrthogonalization.html#BVGetOrthogonalization">BVGetOrthogonalization</A>(), <A HREF="../BV/BVOrthogType.html#BVOrthogType">BVOrthogType</A>, <A HREF="../BV/BVOrthogRefineType.html#BVOrthogRefineType">BVOrthogRefineType</A>, <A HREF="../BV/BVOrthogBlockType.html#BVOrthogBlockType">BVOrthogBlockType</A>
<BR><P><B></B><H3><FONT COLOR="#883300">Level</FONT></H3>advanced<BR>
<H3><FONT COLOR="#883300">Location</FONT></H3>
</B><A HREF="../../../src/sys/classes/bv/interface/bvbasic.c.html#BVSetOrthogonalization">src/sys/classes/bv/interface/bvbasic.c</A>
<BR><BR><A HREF="./index.html">Index of all BV routines</A>
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