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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="PetscSubcomm"><H1>PetscSubcomm</H1></A>
A decomposition of an MPI communicator into subcommunicators
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
typedef struct _n_PetscSubcomm* <A HREF="../Sys/PetscSubcomm.html#PetscSubcomm">PetscSubcomm</A>;
</PRE>
Notes: After a call to <A HREF="../Sys/PetscSubcommSetType.html#PetscSubcommSetType">PetscSubcommSetType</A>(), <A HREF="../Sys/PetscSubcommSetTypeGeneral.html#PetscSubcommSetTypeGeneral">PetscSubcommSetTypeGeneral</A>(), or <A HREF="../Sys/PetscSubcommSetFromOptions.html#PetscSubcommSetFromOptions">PetscSubcommSetFromOptions</A>() one may call
<pre>
PetscSubcommChild() returns the associated subcommunicator on this process
</pre>
<pre>
PetscSubcommContiguousParent() returns a parent communitor but with all child of the same subcommunicator having contiquous rank
</pre>
<P>
<H3><FONT COLOR="#CC3333">Sample Usage</FONT></H3>
<A HREF="../Sys/PetscSubcommCreate.html#PetscSubcommCreate">PetscSubcommCreate</A>()
<A HREF="../Sys/PetscSubcommSetNumber.html#PetscSubcommSetNumber">PetscSubcommSetNumber</A>()
<A HREF="../Sys/PetscSubcommSetType.html#PetscSubcommSetType">PetscSubcommSetType</A>(PETSC_SUBCOMM_INTERLACED);
ccomm = PetscSubcommChild()
<A HREF="../Sys/PetscSubcommDestroy.html#PetscSubcommDestroy">PetscSubcommDestroy</A>()
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
<pre>
PETSC_SUBCOMM_GENERAL - similar to MPI_Comm_split() each process sets the new communicator (color) they will belong to and the order within that communicator
</pre>
<pre>
PETSC_SUBCOMM_CONTIGUOUS - each new communicator contains a set of process with contiquous ranks in the original MPI communicator
</pre>
<pre>
PETSC_SUBCOMM_INTERLACED - each new communictor contains a set of processes equally far apart in rank from the others in that new communicator
</pre>
<P>
Examaple: Consider a communicator with six processes split into 3 subcommunicators.
<pre>
PETSC_SUBCOMM_CONTIGUOUS - the first communicator contains rank 0,1 the second rank 2,3 and the third rank 4,5 in the original ordering of the original communicator
</pre>
<pre>
PETSC_SUBCOMM_INTERLACED - the first communicator contains rank 0,3, the second 1,4 and the third 2,5
</pre>
<P>
Developer Notes: This is used in objects such as <A HREF="../PC/PCREDUNDANT.html#PCREDUNDANT">PCREDUNDANT</A>() to manage the subcommunicators on which the redundant computations
are performed.
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Sys/PetscSubcommCreate.html#PetscSubcommCreate">PetscSubcommCreate</A>(), <A HREF="../Sys/PetscSubcommSetNumber.html#PetscSubcommSetNumber">PetscSubcommSetNumber</A>(), <A HREF="../Sys/PetscSubcommSetType.html#PetscSubcommSetType">PetscSubcommSetType</A>(), PetscSubcommView(), <A HREF="../Sys/PetscSubcommSetFromOptions.html#PetscSubcommSetFromOptions">PetscSubcommSetFromOptions</A>()
<BR>
<P>
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>advanced
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../include/petscsys.h.html#PetscSubcomm">include/petscsys.h</A>
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