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<div id="version" align=right><b>petsc-3.7.5 2017-01-01</b></div>
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<A NAME="PCGASMType"><H1>PCGASMType</H1></A>
Type of generalized additive Schwarz method to use (differs from ASM in allowing multiple processors per subdomain).
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
typedef enum {PC_GASM_BASIC = 3,PC_GASM_RESTRICT = 1,PC_GASM_INTERPOLATE = 2,PC_GASM_NONE = 0} <A HREF="../PC/PCGASMType.html#PCGASMType">PCGASMType</A>;
</PRE>
Each subdomain has nested inner and outer parts. The inner subdomains are assumed to form a non-overlapping covering of the computational
domain, while the outer subdomains contain the inner subdomains and overlap with each other. This preconditioner will compute
a subdomain correction over each *outer* subdomain from a residual computed there, but its different variants will differ in
(a) how the outer subdomain residual is computed, and (b) how the outer subdomain correction is computed.
<P>
<pre>
PC_GASM_BASIC - Symmetric version where the full from the outer subdomain is used, and the resulting correction is applied
</pre>
<pre>
over the outer subdomains. As a result, points in the overlap will receive the sum of the corrections
</pre>
<pre>
from neighboring subdomains.
</pre>
<pre>
Classical standard additive Schwarz.
</pre>
<pre>
PC_GASM_RESTRICT - Residual from the outer subdomain is used but the correction is restricted to the inner subdomain only
</pre>
<pre>
(i.e., zeroed out over the overlap portion of the outer subdomain before being applied). As a result,
</pre>
<pre>
each point will receive a correction only from the unique inner subdomain containing it (nonoverlapping covering
</pre>
<pre>
assumption).
</pre>
<pre>
Default.
</pre>
<pre>
PC_GASM_INTERPOLATE - Residual is zeroed out over the overlap portion of the outer subdomain, but the resulting correction is
</pre>
<pre>
applied over the outer subdomain. As a result, points in the overlap will receive the sum of the corrections
</pre>
<pre>
from neighboring subdomains.
</pre>
<pre>
</pre>
<pre>
PC_GASM_NONE - Residuals and corrections are zeroed out outside the local subdomains.
</pre>
<pre>
Not very good.
</pre>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../PC/PCGASMSetType.html#PCGASMSetType">PCGASMSetType</A>()
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>beginner
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/pc/../../../include/petscpctypes.h.html#PCGASMType">src/ksp/pc/../../../include/petscpctypes.h</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>
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