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<li class="toctree-l2"><a class="reference external" href="https://web.cels.anl.gov/projects/petsc/vault/petsc-3.22/docs"> 3.22</a></li>
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<li class="toctree-l2"><a class="reference external" href="https://web.cels.anl.gov/projects/petsc/vault/petsc-3.3/docs"> 3.3</a></li>
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<section class="tex2jax_ignore mathjax_ignore" id="networks">
<span id="ch-network"></span><h1>Networks<a class="headerlink" href="#networks" title="Link to this heading">#</a></h1>
<p>The <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> class provides
abstractions for representing general unstructured networks such as
communication networks, power grid, computer networks, transportation
networks, electrical circuits, graphs, and others.</p>
<section id="application-flow">
<h2>Application flow<a class="headerlink" href="#application-flow" title="Link to this heading">#</a></h2>
<p>The general flow of an application code using <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> is as
follows:</p>
<ol class="arabic">
<li><p>Create a network object.</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkCreate.html">DMNetworkCreate</a></span><span class="p">(</span><span class="n"><a href="../manualpages/Sys/MPI_Comm.html">MPI_Comm</a></span><span class="w"> </span><span class="n">comm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="o">*</span><span class="n">dm</span><span class="p">);</span>
</pre></div>
</div>
</li>
<li><p>Create components and register them with the network. A “component”
is specific application data at a vertex/edge of the network required
for its residual evaluation. For example, components could be
resistor/inductor data for circuit applications, edge weights for
graph problems, or generator/transmission line data for power grids.
Components are registered by calling</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkRegisterComponent.html">DMNetworkRegisterComponent</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="o">*</span><span class="n">name</span><span class="p">,</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">size</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">compkey</span><span class="p">);</span>
</pre></div>
</div>
<p>Here, <code class="docutils notranslate"><span class="pre">name</span></code> is the component name, <code class="docutils notranslate"><span class="pre">size</span></code> is the size of
component data, and <code class="docutils notranslate"><span class="pre">compkey</span></code> is an integer key that can be
used for setting/getting the component at a vertex or an edge.</p>
</li>
<li><p>A <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> can consist of one or more physical subnetworks. Each subnetwork has its own mathematical model. When
multiple subnetworks are used one can (optionally) provide
coupling information between subnetworks. That is vertices that are <em>shared</em> between multiple subnetworks; edges can only belong to a single subnetwork. The
number of subnetwork is set by calling</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkSetNumSubNetworks.html">DMNetworkSetNumSubNetworks</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">nsubnet</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">Nsubnet</span><span class="p">);</span>
</pre></div>
</div>
<p>Here, <code class="docutils notranslate"><span class="pre">nsubnet</span></code> and <code class="docutils notranslate"><span class="pre">Nsubnet</span></code> are the local and global number of subnetworks.</p>
</li>
<li><p>A subnetwork is added to the network by calling</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkAddSubnetwork.html">DMNetworkAddSubnetwork</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="o">*</span><span class="w"> </span><span class="n">name</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">ne</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">edgelist</span><span class="p">[],</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">netnum</span><span class="p">);</span>
</pre></div>
</div>
<p>Here <code class="docutils notranslate"><span class="pre">name</span></code> is the subnetwork name, <code class="docutils notranslate"><span class="pre">ne</span></code> is the number of local edges on the subnetwork, and <code class="docutils notranslate"><span class="pre">edgelist</span></code> is the connectivity for the subnetwork.
The output <code class="docutils notranslate"><span class="pre">netnum</span></code> is the global numbering of the subnetwork in the network.
Each element of <code class="docutils notranslate"><span class="pre">edgelist</span></code> is an integer array of size <code class="docutils notranslate"><span class="pre">2*ne</span></code>
containing the edge connectivity for the subnetwork.</p>
<p>As an example, consider a network comprised of 2 subnetworks that
are coupled. The topological information for the network is as
follows:</p>
<p>subnetwork 0: v0 — v1 — v2 — v3</p>
<p>subnetwork 1: v1 — v2 — v0</p>
<p>The two subnetworks are coupled by merging vertex 0 from subnetwork 0 with vertex 2 from subnetwork 1.</p>
<p>The</p>
<p><code class="docutils notranslate"><span class="pre">edgelist</span></code></p>
<p>of this network is</p>
<p>edgelist[0] = {0,1,1,2,2,3}</p>
<p>edgelist[1] = {1,2,2,0}</p>
<p>The coupling is done by calling</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkAddSharedVertices.html">DMNetworkAddSharedVertices</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">anet</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">bnet</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">nsv</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">asv</span><span class="p">[],</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">bsv</span><span class="p">[]);</span>
</pre></div>
</div>
<p>Here <code class="docutils notranslate"><span class="pre">anet</span></code> and <code class="docutils notranslate"><span class="pre">bnet</span></code> are the first and second subnetwork global numberings returned by <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNetworkAddSubnetwork.html">DMNetworkAddSubnetwork</a>()</span></code>,
<code class="docutils notranslate"><span class="pre">nsv</span></code> is the number of vertices shared by the two subnetworks, <code class="docutils notranslate"><span class="pre">asv</span></code> and <code class="docutils notranslate"><span class="pre">bsv</span></code> are the vertex indices in the subnetwork <code class="docutils notranslate"><span class="pre">anet</span></code> and <code class="docutils notranslate"><span class="pre">bnet</span></code> .</p>
</li>
<li><p>The next step is to have <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> create a bare layout (graph) of
the network by calling</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkLayoutSetUp.html">DMNetworkLayoutSetUp</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">);</span>
</pre></div>
</div>
</li>
<li><p>After completing the previous steps, the network graph is set up, but
no physics is associated yet. This is done by adding the components
and setting the number of variables to the vertices and edges.</p>
<p>A component and number of variables are added to a vertex/edge by calling</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkAddComponent.html">DMNetworkAddComponent</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">compkey</span><span class="p">,</span><span class="w"> </span><span class="kt">void</span><span class="o">*</span><span class="w"> </span><span class="n">compdata</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">nvar</span><span class="p">)</span>
</pre></div>
</div>
<p>where <code class="docutils notranslate"><span class="pre">p</span></code> is the network vertex/edge point in the range obtained by
either <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNetworkGetVertexRange.html">DMNetworkGetVertexRange</a>()</span></code>/<code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNetworkGetEdgeRange.html">DMNetworkGetEdgeRange</a>()</span></code>, <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNetworkGetSubnetwork.html">DMNetworkGetSubnetwork</a>()</span></code>, or <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNetworkGetSharedVertices.html">DMNetworkGetSharedVertices</a>()</span></code>;
<code class="docutils notranslate"><span class="pre">compkey</span></code> is the component key returned when registering the component
(<code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNetworkRegisterComponent.html">DMNetworkRegisterComponent</a>()</span></code>); <code class="docutils notranslate"><span class="pre">compdata</span></code> holds the data for the
component; and <code class="docutils notranslate"><span class="pre">nvar</span></code> is the number of variables associated to the added component at this network point. <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> supports setting multiple components
at a vertex/edge. At a shared vertex, <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> currently requires the owner process of the vertex adds all the components and number of variables.</p>
<p><code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> currently assumes the component data to be stored in a
contiguous chunk of memory. As such, it does not do any
packing/unpacking before/after the component data gets distributed.
Any such serialization (packing/unpacking) should be done by the
application.</p>
</li>
<li><p>Set up network internal data structures.</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DM/DMSetUp.html">DMSetUp</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">);</span>
</pre></div>
</div>
</li>
<li><p>Distribute the network (also moves components attached with
vertices/edges) to multiple processors.</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkDistribute.html">DMNetworkDistribute</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="n">partitioner</span><span class="p">[],</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">overlap</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="o">*</span><span class="n">distDM</span><span class="p">);</span>
</pre></div>
</div>
</li>
<li><p>Associate the <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DM/DM.html">DM</a></span></code> with a PETSc solver:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/KSP/KSPSetDM.html">KSPSetDM</a></span><span class="p">(</span><span class="n"><a href="../manualpages/KSP/KSP.html">KSP</a></span><span class="w"> </span><span class="n">ksp</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">)</span><span class="w"> </span><span class="n">or</span><span class="w"> </span><span class="n"><a href="../manualpages/SNES/SNESSetDM.html">SNESSetDM</a></span><span class="p">(</span><span class="n"><a href="../manualpages/SNES/SNES.html">SNES</a></span><span class="w"> </span><span class="n">snes</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">)</span><span class="w"> </span><span class="n">or</span><span class="w"> </span><span class="n"><a href="../manualpages/TS/TSSetDM.html">TSSetDM</a></span><span class="p">(</span><span class="n"><a href="../manualpages/TS/TS.html">TS</a></span><span class="w"> </span><span class="n">ts</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">).</span>
</pre></div>
</div>
</li>
</ol>
</section>
<section id="utility-functions">
<h2>Utility functions<a class="headerlink" href="#utility-functions" title="Link to this heading">#</a></h2>
<p><code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNETWORK.html">DMNETWORK</a></span></code> provides several utility functions for operations on the
network. The most commonly used functions are: obtaining iterators for
vertices/edges,</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetEdgeRange.html">DMNetworkGetEdgeRange</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">eStart</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">eEnd</span><span class="p">);</span>
</pre></div>
</div>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetVertexRange.html">DMNetworkGetVertexRange</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">vStart</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">vEnd</span><span class="p">);</span>
</pre></div>
</div>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetSubnetwork.html">DMNetworkGetSubnetwork</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">netnum</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">nv</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">ne</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">**</span><span class="n">vtx</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">**</span><span class="n">edge</span><span class="p">);</span>
</pre></div>
</div>
<p>checking the status of a vertex,</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkIsGhostVertex.html">DMNetworkIsGhostVertex</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscBool.html">PetscBool</a></span><span class="w"> </span><span class="o">*</span><span class="n">isghost</span><span class="p">);</span>
</pre></div>
</div>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkIsSharedVertex.html">DMNetworkIsSharedVertex</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscBool.html">PetscBool</a></span><span class="w"> </span><span class="o">*</span><span class="n">isshared</span><span class="p">);</span>
</pre></div>
</div>
<p>and retrieving local/global indices of vertex/edge component variables for
inserting elements in vectors/matrices,</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetLocalVecOffset.html">DMNetworkGetLocalVecOffset</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">compnum</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">offset</span><span class="p">);</span>
</pre></div>
</div>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetGlobalVecOffset.html">DMNetworkGetGlobalVecOffset</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">compnum</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">offsetg</span><span class="p">).</span>
</pre></div>
</div>
<p>In network applications, one frequently needs to find the supporting
edges for a vertex or the connecting vertices covering an edge. These
can be obtained by the following two routines.</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetConnectedVertices.html">DMNetworkGetConnectedVertices</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">edge</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">vertices</span><span class="p">[]);</span>
</pre></div>
</div>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetSupportingEdges.html">DMNetworkGetSupportingEdges</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">vertex</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">nedges</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">edges</span><span class="p">[]).</span>
</pre></div>
</div>
</section>
<section id="retrieving-components-and-number-of-variables">
<h2>Retrieving components and number of variables<a class="headerlink" href="#retrieving-components-and-number-of-variables" title="Link to this heading">#</a></h2>
<p>The components and the corresponding number of variables set at a vertex/edge can be accessed by</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetComponent.html">DMNetworkGetComponent</a></span><span class="p">(</span><span class="n"><a href="../manualpages/DM/DM.html">DM</a></span><span class="w"> </span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">compnum</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">compkey</span><span class="p">,</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="o">**</span><span class="n">component</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="o">*</span><span class="n">nvar</span><span class="p">)</span>
</pre></div>
</div>
<p>input <code class="docutils notranslate"><span class="pre">compnum</span></code> is the component number, output <code class="docutils notranslate"><span class="pre">compkey</span></code> is the key set by <code class="docutils notranslate"><span class="pre"><a href="../manualpages/DMNetwork/DMNetworkRegisterComponent.html">DMNetworkRegisterComponent</a>()</span></code>. An example
of accessing and retrieving the components and number of variables at vertices is:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n"><a href="../manualpages/Sys/PetscInt.html">PetscInt</a></span><span class="w"> </span><span class="n">Start</span><span class="p">,</span><span class="n">End</span><span class="p">,</span><span class="n">numcomps</span><span class="p">,</span><span class="n">key</span><span class="p">,</span><span class="n">v</span><span class="p">,</span><span class="n">compnum</span><span class="p">;</span>
<span class="kt">void</span><span class="w"> </span><span class="o">*</span><span class="n">component</span><span class="p">;</span>
<span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetVertexRange.html">DMNetworkGetVertexRange</a></span><span class="p">(</span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">Start</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">End</span><span class="p">);</span>
<span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">v</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Start</span><span class="p">;</span><span class="w"> </span><span class="n">v</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">End</span><span class="p">;</span><span class="w"> </span><span class="n">v</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetNumComponents.html">DMNetworkGetNumComponents</a></span><span class="p">(</span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n">v</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">numcomps</span><span class="p">);</span>
<span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">compnum</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">compnum</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">numcomps</span><span class="p">;</span><span class="w"> </span><span class="n">compnum</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../manualpages/DMNetwork/DMNetworkGetComponent.html">DMNetworkGetComponent</a></span><span class="p">(</span><span class="n">dm</span><span class="p">,</span><span class="w"> </span><span class="n">v</span><span class="p">,</span><span class="w"> </span><span class="n">compnum</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">key</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">component</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">nvar</span><span class="p">);</span>
<span class="w"> </span><span class="n">compdata</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">UserCompDataType</span><span class="p">)(</span><span class="n">component</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>The above example does not explicitly use the component key. It is
used when different component types are set at different vertices. In
this case, <code class="docutils notranslate"><span class="pre">compkey</span></code> is used to differentiate the component type.</p>
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