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<div id="version" align=right><b>petsc-3.14.5 2021-03-03</b></div>
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<A NAME="MatCreateMPIAIJWithSplitArrays"><H1>MatCreateMPIAIJWithSplitArrays</H1></A>
creates a MPI AIJ matrix using arrays that contain the "diagonal" and "off-diagonal" part of the matrix in CSR format.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscmat.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../Mat/MatCreateMPIAIJWithSplitArrays.html#MatCreateMPIAIJWithSplitArrays">MatCreateMPIAIJWithSplitArrays</A>(<A HREF="../Sys/MPI_Comm.html#MPI_Comm">MPI_Comm</A> comm,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> m,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> n,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> M,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> N,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> i[],<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> j[],<A HREF="../Sys/PetscScalar.html#PetscScalar">PetscScalar</A> a[],<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> oi[], <A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> oj[],<A HREF="../Sys/PetscScalar.html#PetscScalar">PetscScalar</A> oa[],<A HREF="../Mat/Mat.html#Mat">Mat</A> *mat)
</PRE>
Collective
<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>comm </B></TD><TD>- MPI communicator
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>m </B></TD><TD>- number of local rows (Cannot be <A HREF="../Sys/PETSC_DECIDE.html#PETSC_DECIDE">PETSC_DECIDE</A>)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>n </B></TD><TD>- This value should be the same as the local size used in creating the
x vector for the matrix-vector product y = Ax. (or <A HREF="../Sys/PETSC_DECIDE.html#PETSC_DECIDE">PETSC_DECIDE</A> to have
calculated if N is given) For square matrices n is almost always m.
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>M </B></TD><TD>- number of global rows (or <A HREF="../Sys/PETSC_DETERMINE.html#PETSC_DETERMINE">PETSC_DETERMINE</A> to have calculated if m is given)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>N </B></TD><TD>- number of global columns (or <A HREF="../Sys/PETSC_DETERMINE.html#PETSC_DETERMINE">PETSC_DETERMINE</A> to have calculated if n is given)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>i </B></TD><TD>- row indices for "diagonal" portion of matrix; that is i[0] = 0, i[row] = i[row-1] + number of elements in that row of the matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>j </B></TD><TD>- column indices
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>a </B></TD><TD>- matrix values
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>oi </B></TD><TD>- row indices for "off-diagonal" portion of matrix; that is oi[0] = 0, oi[row] = oi[row-1] + number of elements in that row of the matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>oj </B></TD><TD>- column indices
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>oa </B></TD><TD>- matrix values
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>mat </B></TD><TD>- the matrix
</TD></TR></TABLE>
<P>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
The i, j, and a arrays ARE NOT copied by this routine into the internal format used by PETSc. The user
must free the arrays once the matrix has been destroyed and not before.
<P>
The i and j indices are 0 based
<P>
See <A HREF="../Mat/MatCreateAIJ.html#MatCreateAIJ">MatCreateAIJ</A>() for the definition of "diagonal" and "off-diagonal" portion of the matrix
<P>
This sets local rows and cannot be used to set off-processor values.
<P>
Use of this routine is discouraged because it is inflexible and cumbersome to use. It is extremely rare that a
legacy application natively assembles into exactly this split format. The code to do so is nontrivial and does
not easily support in-place reassembly. It is recommended to use <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>() (or a variant thereof) because
the resulting assembly is easier to implement, will work with any matrix format, and the user does not have to
keep track of the underlying array. Use <A HREF="../Mat/MatSetOption.html#MatSetOption">MatSetOption</A>(A,<A HREF="../Mat/MatOption.html#MatOption">MAT_NO_OFF_PROC_ENTRIES</A>,<A HREF="../Sys/PETSC_TRUE.html#PETSC_TRUE">PETSC_TRUE</A>) to disable all
communication if it is known that only local entries will be set.
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Mat/MatCreate.html#MatCreate">MatCreate</A>(), <A HREF="../Mat/MatCreateSeqAIJ.html#MatCreateSeqAIJ">MatCreateSeqAIJ</A>(), <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>(), <A HREF="../Mat/MatMPIAIJSetPreallocation.html#MatMPIAIJSetPreallocation">MatMPIAIJSetPreallocation</A>(), <A HREF="../Mat/MatMPIAIJSetPreallocationCSR.html#MatMPIAIJSetPreallocationCSR">MatMPIAIJSetPreallocationCSR</A>(),
<BR><A HREF="../Mat/MATMPIAIJ.html#MATMPIAIJ">MATMPIAIJ</A>, <A HREF="../Mat/MatCreateAIJ.html#MatCreateAIJ">MatCreateAIJ</A>(), <A HREF="../Mat/MatCreateMPIAIJWithArrays.html#MatCreateMPIAIJWithArrays">MatCreateMPIAIJWithArrays</A>()
<P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>advanced<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/mat/impls/aij/mpi/mpiaij.c.html#MatCreateMPIAIJWithSplitArrays">src/mat/impls/aij/mpi/mpiaij.c</A>
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