1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML3.2 EN">
<HTML>
<HEAD> <link rel="canonical" href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCGASMSetOverlap.html" />
<META NAME="GENERATOR" CONTENT="DOCTEXT">
<TITLE>PCGASMSetOverlap</TITLE>
</HEAD>
<BODY BGCOLOR="FFFFFF">
<div id="version" align=right><b>petsc-3.4.2 2013-07-02</b></div>
<A NAME="PCGASMSetOverlap"><H1>PCGASMSetOverlap</H1></A>
Sets the overlap between a pair of subdomains for the additive Schwarz preconditioner. Either all or no processors in the <A HREF="../PC/PC.html#PC">PC</A> communicator must call this routine.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscpc.h"
PetscErrorCode PCGASMSetOverlap(PC pc,PetscInt ovl)
</PRE>
Logically Collective on <A HREF="../PC/PC.html#PC">PC</A>
<P>
<H3><FONT COLOR="#CC3333">Input Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>pc </B></TD><TD>- the preconditioner context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ovl </B></TD><TD>- the amount of overlap between subdomains (ovl >= 0, default value = 1)
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database Key</FONT></H3>
<DT><B>-pc_gasm_overlap <overlap> </B> -Sets overlap
<br>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
By default the GASM preconditioner uses 1 subdomain per processor. To use
multiple subdomain per perocessor, see <A HREF="../PC/PCGASMSetTotalSubdomains.html#PCGASMSetTotalSubdomains">PCGASMSetTotalSubdomains</A>() or
<A HREF="../PC/PCGASMSetSubdomains.html#PCGASMSetSubdomains">PCGASMSetSubdomains</A>() (and the option -pc_gasm_total_subdomains <n>).
<P>
The overlap defaults to 1, so if one desires that no additional
overlap be computed beyond what may have been set with a call to
<A HREF="../PC/PCGASMSetTotalSubdomains.html#PCGASMSetTotalSubdomains">PCGASMSetTotalSubdomains</A>() or <A HREF="../PC/PCGASMSetSubdomains.html#PCGASMSetSubdomains">PCGASMSetSubdomains</A>(), then ovl
must be set to be 0. In particular, if one does not explicitly set
the subdomains in application code, then all overlap would be computed
internally by PETSc, and using an overlap of 0 would result in an GASM
variant that is equivalent to the block Jacobi preconditioner.
<P>
Note that one can define initial index sets with any overlap via
<A HREF="../PC/PCGASMSetSubdomains.html#PCGASMSetSubdomains">PCGASMSetSubdomains</A>(); the routine <A HREF="../PC/PCGASMSetOverlap.html#PCGASMSetOverlap">PCGASMSetOverlap</A>() merely allows
PETSc to extend that overlap further, if desired.
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../PC/PC.html#PC">PC</A>, GASM, set, overlap
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../PC/PCGASMSetTotalSubdomains.html#PCGASMSetTotalSubdomains">PCGASMSetTotalSubdomains</A>(), <A HREF="../PC/PCGASMSetSubdomains.html#PCGASMSetSubdomains">PCGASMSetSubdomains</A>(), <A HREF="../PC/PCGASMGetSubKSP.html#PCGASMGetSubKSP">PCGASMGetSubKSP</A>(),
<BR><A HREF="../PC/PCGASMCreateSubdomains2D.html#PCGASMCreateSubdomains2D">PCGASMCreateSubdomains2D</A>(), <A HREF="../PC/PCGASMGetSubdomains.html#PCGASMGetSubdomains">PCGASMGetSubdomains</A>()
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>intermediate
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/pc/impls/gasm/gasm.c.html#PCGASMSetOverlap">src/ksp/pc/impls/gasm/gasm.c</A>
<BR><A HREF="./index.html">Index of all PC routines</A>
<BR><A HREF="../../index.html">Table of Contents for all manual pages</A>
<BR><A HREF="../singleindex.html">Index of all manual pages</A>
<P><H3><FONT COLOR="#CC3333">Examples</FONT></H3>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex8g.c.html">src/ksp/ksp/examples/tutorials/ex8g.c.html</A><BR>
</BODY></HTML>
|
