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
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML3.2 EN">
<HTML>
<HEAD> <link rel="canonical" href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatGetRow.html" />
<META NAME="GENERATOR" CONTENT="DOCTEXT">
<TITLE>MatGetRow</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/Mat/MatGetRow.html "><small>Report Typos and Errors</small></a></div>
<A NAME="MatGetRow"><H1>MatGetRow</H1></A>
Gets a row of a matrix. You MUST call <A HREF="../Mat/MatRestoreRow.html#MatRestoreRow">MatRestoreRow</A>() for each row that you get to ensure that your application does not bleed memory.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscmat.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../Mat/MatGetRow.html#MatGetRow">MatGetRow</A>(<A HREF="../Mat/Mat.html#Mat">Mat</A> mat,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> row,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> *ncols,const <A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> *cols[],const <A HREF="../Sys/PetscScalar.html#PetscScalar">PetscScalar</A> *vals[])
</PRE>
Not 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>mat </B></TD><TD>- the matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>row </B></TD><TD>- the row to get
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ncols </B></TD><TD>- if not NULL, the number of nonzeros in the row
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>cols </B></TD><TD>- if not NULL, the column numbers
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>vals </B></TD><TD>- if not NULL, the values
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
This routine is provided for people who need to have direct access
to the structure of a matrix. We hope that we provide enough
high-level matrix routines that few users will need it.
<P>
<A HREF="../Mat/MatGetRow.html#MatGetRow">MatGetRow</A>() always returns 0-based column indices, regardless of
whether the internal representation is 0-based (default) or 1-based.
<P>
For better efficiency, set cols and/or vals to NULL if you do
not wish to extract these quantities.
<P>
The user can only examine the values extracted with <A HREF="../Mat/MatGetRow.html#MatGetRow">MatGetRow</A>();
the values cannot be altered. To change the matrix entries, one
must use <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>().
<P>
You can only have one call to <A HREF="../Mat/MatGetRow.html#MatGetRow">MatGetRow</A>() outstanding for a particular
matrix at a time, per processor. <A HREF="../Mat/MatGetRow.html#MatGetRow">MatGetRow</A>() can only obtain rows
associated with the given processor, it cannot get rows from the
other processors; for that we suggest using <A HREF="../Mat/MatCreateSubMatrices.html#MatCreateSubMatrices">MatCreateSubMatrices</A>(), then
<A HREF="../Mat/MatGetRow.html#MatGetRow">MatGetRow</A>() on the submatrix. The row index passed to MatGetRows()
is in the global number of rows.
<P>
<H3><FONT COLOR="#CC3333">Fortran Notes</FONT></H3>
The calling sequence from Fortran is
<PRE>
<A HREF="../Mat/MatGetRow.html#MatGetRow">MatGetRow</A>(matrix,row,ncols,cols,values,ierr)
<A HREF="../Mat/Mat.html#Mat">Mat</A> matrix (input)
integer row (input)
integer ncols (output)
integer cols(maxcols) (output)
double precision (or double complex) values(maxcols) output
</PRE>
where maxcols >= maximum nonzeros in any row of the matrix.
<P>
<P>
<H3><FONT COLOR="#CC3333">Caution</FONT></H3>
Do not try to change the contents of the output arrays (cols and vals).
In some cases, this may corrupt the matrix.
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Mat/MatRestoreRow.html#MatRestoreRow">MatRestoreRow</A>(), <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>(), <A HREF="../Mat/MatGetValues.html#MatGetValues">MatGetValues</A>(), <A HREF="../Mat/MatCreateSubMatrices.html#MatCreateSubMatrices">MatCreateSubMatrices</A>(), <A HREF="../Mat/MatGetDiagonal.html#MatGetDiagonal">MatGetDiagonal</A>()
<BR><P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>advanced<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/mat/interface/matrix.c.html#MatGetRow">src/mat/interface/matrix.c</A>
<P><H3><FONT COLOR="#CC3333">Examples</FONT></H3>
<A HREF="../../../src/mat/examples/tutorials/ex12.c.html">src/mat/examples/tutorials/ex12.c.html</A><BR>
<A HREF="../../../src/mat/examples/tutorials/ex16.c.html">src/mat/examples/tutorials/ex16.c.html</A><BR>
<P><H3><FONT COLOR="CC3333">Implementations</FONT></H3><A HREF="../../../src/mat/impls/adj/mpi/mpiadj.c.html#MatGetRow_MPIAdj">MatGetRow_MPIAdj in src/mat/impls/adj/mpi/mpiadj.c</A><BR>
<A HREF="../../../src/mat/impls/aij/mpi/mpiaij.c.html#MatGetRow_MPIAIJ">MatGetRow_MPIAIJ in src/mat/impls/aij/mpi/mpiaij.c</A><BR>
<A HREF="../../../src/mat/impls/aij/seq/aij.c.html#MatGetRow_SeqAIJ">MatGetRow_SeqAIJ in src/mat/impls/aij/seq/aij.c</A><BR>
<A HREF="../../../src/mat/impls/baij/mpi/mpibaij.c.html#MatGetRow_MPIBAIJ">MatGetRow_MPIBAIJ in src/mat/impls/baij/mpi/mpibaij.c</A><BR>
<A HREF="../../../src/mat/impls/baij/seq/baij.c.html#MatGetRow_SeqBAIJ_private">MatGetRow_SeqBAIJ_private in src/mat/impls/baij/seq/baij.c</A><BR>
<A HREF="../../../src/mat/impls/baij/seq/baij.c.html#MatGetRow_SeqBAIJ">MatGetRow_SeqBAIJ in src/mat/impls/baij/seq/baij.c</A><BR>
<A HREF="../../../src/mat/impls/dense/mpi/mpidense.c.html#MatGetRow_MPIDense">MatGetRow_MPIDense in src/mat/impls/dense/mpi/mpidense.c</A><BR>
<A HREF="../../../src/mat/impls/dense/seq/dense.c.html#MatGetRow_SeqDense">MatGetRow_SeqDense in src/mat/impls/dense/seq/dense.c</A><BR>
<A HREF="../../../src/mat/impls/hypre/mhypre.c.html#MatGetRow_HYPRE">MatGetRow_HYPRE in src/mat/impls/hypre/mhypre.c</A><BR>
<A HREF="../../../src/mat/impls/sbaij/mpi/mpisbaij.c.html#MatGetRow_MPISBAIJ">MatGetRow_MPISBAIJ in src/mat/impls/sbaij/mpi/mpisbaij.c</A><BR>
<A HREF="../../../src/mat/impls/sbaij/seq/sbaij.c.html#MatGetRow_SeqSBAIJ">MatGetRow_SeqSBAIJ in src/mat/impls/sbaij/seq/sbaij.c</A><BR>
<A HREF="../../../src/mat/impls/sell/seq/sell.c.html#MatGetRow_SeqSELL">MatGetRow_SeqSELL in src/mat/impls/sell/seq/sell.c</A><BR>
<BR><A HREF="./index.html">Index of all Mat 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>
|
