mirror of
https://github.com/sfilippone/amg4psblas.git
synced 2026-10-06 22:55:12 +00:00
mld2p4:
copyright and internal doc adjustments for version 1.1.
This commit is contained in:
+25
-25
@@ -62,7 +62,7 @@ Smoothed Aggregation
|
||||
<P>
|
||||
In order to define the restriction operator <IMG
|
||||
WIDTH="29" HEIGHT="32" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img67.png"
|
||||
SRC="img68.png"
|
||||
ALT="$R_C$">, which is used to compute
|
||||
the coarse-level matrix <IMG
|
||||
WIDTH="29" HEIGHT="32" ALIGN="MIDDLE" BORDER="0"
|
||||
@@ -81,7 +81,7 @@ The basic idea of this algorithm is to build a coarse set of vertices
|
||||
ALT="$W$"> into disjoint subsets
|
||||
(aggregates), and to define the coarse-to-fine space transfer operator <IMG
|
||||
WIDTH="29" HEIGHT="40" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img68.png"
|
||||
SRC="img69.png"
|
||||
ALT="$R_C^T$"> by
|
||||
applying a suitable smoother to a simple piecewise constant
|
||||
prolongation operator, to improve the quality of the coarse-space correction.
|
||||
@@ -100,15 +100,15 @@ Three main steps can be identified in the smoothed aggregation procedure:
|
||||
</LI>
|
||||
<LI>construction of the prolongator <IMG
|
||||
WIDTH="29" HEIGHT="40" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img68.png"
|
||||
SRC="img69.png"
|
||||
ALT="$R_C^T$">;
|
||||
</LI>
|
||||
<LI>application of <IMG
|
||||
WIDTH="29" HEIGHT="32" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img67.png"
|
||||
SRC="img68.png"
|
||||
ALT="$R_C$"> and <IMG
|
||||
WIDTH="29" HEIGHT="40" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img68.png"
|
||||
SRC="img69.png"
|
||||
ALT="$R_C^T$"> to build <IMG
|
||||
WIDTH="29" HEIGHT="32" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img43.png"
|
||||
@@ -124,14 +124,14 @@ in [<A
|
||||
this algorithm has been actually considered,
|
||||
in which each aggregate <IMG
|
||||
WIDTH="26" HEIGHT="32" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img69.png"
|
||||
SRC="img70.png"
|
||||
ALT="$N_r$"> is made of vertices of <IMG
|
||||
WIDTH="24" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img10.png"
|
||||
ALT="$W$"> that are <I>strongly coupled</I>
|
||||
to a certain root vertex <IMG
|
||||
WIDTH="53" HEIGHT="32" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img70.png"
|
||||
SRC="img71.png"
|
||||
ALT="$r \in W$">, i.e. <BR><P></P>
|
||||
<DIV ALIGN="CENTER">
|
||||
<!-- MATH
|
||||
@@ -143,7 +143,7 @@ N_r = \left\{s \in W: |a_{rs}| > \theta \sqrt{|a_{rr}a_{ss}|} \right\}
|
||||
|
||||
<IMG
|
||||
WIDTH="319" HEIGHT="38" BORDER="0"
|
||||
SRC="img71.png"
|
||||
SRC="img72.png"
|
||||
ALT="\begin{displaymath}N_r = \left\{s \in W: \vert a_{rs}\vert > \theta \sqrt{\vert a_{rr}a_{ss}\vert} \right\}
|
||||
\cup \left\{ r \right\} ,
|
||||
\end{displaymath}">
|
||||
@@ -155,16 +155,16 @@ for a given <!-- MATH
|
||||
-->
|
||||
<IMG
|
||||
WIDTH="69" HEIGHT="36" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img72.png"
|
||||
SRC="img73.png"
|
||||
ALT="$\theta \in [0,1]$">.
|
||||
Since this algorithm has a sequential nature, a <I>decoupled</I> version of
|
||||
it has been chosen, where each processor <IMG
|
||||
WIDTH="10" HEIGHT="18" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img73.png"
|
||||
WIDTH="11" HEIGHT="18" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img74.png"
|
||||
ALT="$i$"> independently applies the algorithm to
|
||||
the set of vertices <IMG
|
||||
WIDTH="31" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img74.png"
|
||||
SRC="img75.png"
|
||||
ALT="$W_i^0$"> assigned to it in the initial data distribution. This
|
||||
version is embarrassingly parallel, since it does not require any data communication.
|
||||
On the other hand, it may produce non-uniform aggregates near boundary vertices,
|
||||
@@ -183,14 +183,14 @@ since it has been shown to produce good results in practice
|
||||
<P>
|
||||
The prolongator <IMG
|
||||
WIDTH="75" HEIGHT="40" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img75.png"
|
||||
SRC="img76.png"
|
||||
ALT="$P_C=R_C^T$"> is built starting from a <I>tentative prolongator</I>
|
||||
<!-- MATH
|
||||
$P \in \Re^{n \times n_C}$
|
||||
-->
|
||||
<IMG
|
||||
WIDTH="90" HEIGHT="38" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img76.png"
|
||||
WIDTH="89" HEIGHT="38" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img77.png"
|
||||
ALT="$P \in \Re^{n \times n_C}$">, defined as
|
||||
<BR>
|
||||
<DIV ALIGN="RIGHT">
|
||||
@@ -207,7 +207,7 @@ P=(p_{ij}), \quad p_{ij}=
|
||||
<TABLE WIDTH="100%" ALIGN="CENTER">
|
||||
<TR VALIGN="MIDDLE"><TD ALIGN="CENTER" NOWRAP><A NAME="eq:tent_prol"></A><IMG
|
||||
WIDTH="290" HEIGHT="52" BORDER="0"
|
||||
SRC="img77.png"
|
||||
SRC="img78.png"
|
||||
ALT="\begin{displaymath}
|
||||
P=(p_{ij}), \quad p_{ij}=
|
||||
\left\{ \begin{array}{ll}
|
||||
@@ -222,17 +222,17 @@ P=(p_{ij}), \quad p_{ij}=
|
||||
<BR CLEAR="ALL"></DIV><P></P>
|
||||
<IMG
|
||||
WIDTH="27" HEIGHT="32" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img78.png"
|
||||
SRC="img79.png"
|
||||
ALT="$P_C$"> is obtained by
|
||||
applying to <IMG
|
||||
WIDTH="18" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img79.png"
|
||||
SRC="img80.png"
|
||||
ALT="$P$"> a smoother <!-- MATH
|
||||
$S \in \Re^{n \times n}$
|
||||
-->
|
||||
<IMG
|
||||
WIDTH="78" HEIGHT="38" ALIGN="MIDDLE" BORDER="0"
|
||||
SRC="img80.png"
|
||||
SRC="img81.png"
|
||||
ALT="$S \in \Re^{n \times n}$">:
|
||||
<BR>
|
||||
<DIV ALIGN="RIGHT">
|
||||
@@ -245,7 +245,7 @@ P_C = S P,
|
||||
<TABLE WIDTH="100%" ALIGN="CENTER">
|
||||
<TR VALIGN="MIDDLE"><TD ALIGN="CENTER" NOWRAP><A NAME="eq:smoothed_prol"></A><IMG
|
||||
WIDTH="73" HEIGHT="30" BORDER="0"
|
||||
SRC="img81.png"
|
||||
SRC="img82.png"
|
||||
ALT="\begin{displaymath}
|
||||
P_C = S P,
|
||||
\end{displaymath}"></TD>
|
||||
@@ -260,7 +260,7 @@ Schwarz method [<A
|
||||
HREF="node25.html#StubenGMD69_99">22</A>].
|
||||
A simple choice for <IMG
|
||||
WIDTH="16" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img82.png"
|
||||
SRC="img83.png"
|
||||
ALT="$S$"> is the damped Jacobi smoother:
|
||||
<BR>
|
||||
<DIV ALIGN="RIGHT">
|
||||
@@ -273,7 +273,7 @@ S = I - \omega D^{-1} A ,
|
||||
<TABLE WIDTH="100%" ALIGN="CENTER">
|
||||
<TR VALIGN="MIDDLE"><TD ALIGN="CENTER" NOWRAP><A NAME="eq:jac_smoother"></A><IMG
|
||||
WIDTH="126" HEIGHT="30" BORDER="0"
|
||||
SRC="img83.png"
|
||||
SRC="img84.png"
|
||||
ALT="\begin{displaymath}
|
||||
S = I - \omega D^{-1} A ,
|
||||
\end{displaymath}"></TD>
|
||||
@@ -283,11 +283,11 @@ S = I - \omega D^{-1} A ,
|
||||
<BR CLEAR="ALL"></DIV><P></P>
|
||||
where the value of <IMG
|
||||
WIDTH="16" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img84.png"
|
||||
SRC="img85.png"
|
||||
ALT="$\omega$"> can be chosen
|
||||
using some estimate of the spectral radius of <IMG
|
||||
WIDTH="50" HEIGHT="21" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img85.png"
|
||||
WIDTH="51" HEIGHT="21" ALIGN="BOTTOM" BORDER="0"
|
||||
SRC="img86.png"
|
||||
ALT="$D^{-1}A$"> [<A
|
||||
HREF="node25.html#BREZINA_VANEK">1</A>].
|
||||
|
||||
|
||||
Reference in New Issue
Block a user