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/KSP/KSPChebyshevEstEigSet.html" />
<META NAME="GENERATOR" CONTENT="DOCTEXT">
<TITLE>KSPChebyshevEstEigSet</TITLE>
</HEAD>
<BODY BGCOLOR="FFFFFF">
<div id="version" align=right><b>petsc-3.10.3 2018-12-18</b></div>
<div id="bugreport" align=right><a href="mailto:petsc-maint@mcs.anl.gov?subject=Typo or Error in Documentation &body=Please describe the typo or error in the documentation: petsc-3.10.3 v3.10.3 docs/manualpages/KSP/KSPChebyshevEstEigSet.html "><small>Report Typos and Errors</small></a></div>
<A NAME="KSPChebyshevEstEigSet"><H1>KSPChebyshevEstEigSet</H1></A>
Automatically estimate the eigenvalues to use for Chebyshev
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscksp.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../KSP/KSPChebyshevEstEigSet.html#KSPChebyshevEstEigSet">KSPChebyshevEstEigSet</A>(<A HREF="../KSP/KSP.html#KSP">KSP</A> ksp,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> a,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> b,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> c,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> d)
</PRE>
Logically Collective on <A HREF="../KSP/KSP.html#KSP">KSP</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>ksp </B></TD><TD>- the Krylov space context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>a </B></TD><TD>- multiple of min eigenvalue estimate to use for min Chebyshev bound (or <A HREF="../Sys/PETSC_DECIDE.html#PETSC_DECIDE">PETSC_DECIDE</A>)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>b </B></TD><TD>- multiple of max eigenvalue estimate to use for min Chebyshev bound (or <A HREF="../Sys/PETSC_DECIDE.html#PETSC_DECIDE">PETSC_DECIDE</A>)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>c </B></TD><TD>- multiple of min eigenvalue estimate to use for max Chebyshev bound (or <A HREF="../Sys/PETSC_DECIDE.html#PETSC_DECIDE">PETSC_DECIDE</A>)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>d </B></TD><TD>- multiple of max eigenvalue estimate to use for max Chebyshev bound (or <A HREF="../Sys/PETSC_DECIDE.html#PETSC_DECIDE">PETSC_DECIDE</A>)
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database</FONT></H3>
<DT><B>-ksp_chebyshev_esteig a,b,c,d</B> -
Notes:
The Chebyshev bounds are set using
<br>
<PRE>
minbound = a*minest + b*maxest
maxbound = c*minest + d*maxest
</PRE>
The default configuration targets the upper part of the spectrum for use as a multigrid smoother, so only the maximum eigenvalue estimate is used.
The minimum eigenvalue estimate obtained by Krylov iteration is typically not accurate until the method has converged.
<P>
If 0.0 is passed for all transform arguments (a,b,c,d), eigenvalue estimation is disabled.
<P>
The default transform is (0,0.1; 0,1.1) which targets the "upper" part of the spectrum, as desirable for use with multigrid.
<P>
The eigenvalues are estimated using the Lanczo (<A HREF="../KSP/KSPCG.html#KSPCG">KSPCG</A>) or Arnoldi (<A HREF="../KSP/KSPGMRES.html#KSPGMRES">KSPGMRES</A>) process using a noisy right hand side vector.
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../KSP/KSP.html#KSP">KSP</A>, Chebyshev, set, eigenvalues, <A HREF="../PC/PCMG.html#PCMG">PCMG</A>
<BR><P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>intermediate<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/ksp/ksp/impls/cheby/cheby.c.html#KSPChebyshevEstEigSet">src/ksp/ksp/impls/cheby/cheby.c</A>
<P><H3><FONT COLOR="CC3333">Implementations</FONT></H3><A HREF="../../../src/ksp/ksp/impls/cheby/cheby.c.html#KSPChebyshevEstEigSet_Chebyshev">KSPChebyshevEstEigSet_Chebyshev in src/ksp/ksp/impls/cheby/cheby.c</A><BR>
<BR><A HREF="./index.html">Index of all KSP 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>
</BODY></HTML>
|
