<HTML>
<!--
     Copyright (c) Jeremy Siek 2000
    
     Distributed under the Boost Software License, Version 1.0.
     (See accompanying file LICENSE_1_0.txt or copy at
     http://www.boost.org/LICENSE_1_0.txt)
  -->
<Head>
<Title>AdjacencyMatrix</Title>
<BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" 
        ALINK="#ff0000"> 
<IMG SRC="../../../boost.png" 
     ALT="C++ Boost" width="277" height="86"> 

<BR Clear>


<H2><A NAME="concept:AdjacencyMatrix"></A>
AdjacencyMatrix
</H2>

<P>
The AdjacencyMatrix concept refines <a href="./Graph.html">Graph</a>
concept and adds the requirement for efficient access to any edge in
the graph given the source and target vertices. No Boost Graph Library
algorithms currently use this concept. However there are algorithms
not yet implemented such as Floyd-Warshall that would require this
concept.

<H3>Refinement of</H3>

<a href="./Graph.html">Graph</a>

<H3>Associated Types</H3>

<Table border>

<tr>
<td><tt>boost::graph_traits&lt;G&gt;::traversal_category</tt><br><br>
 This tag type must be convertible to <tt>adjacency_matrix_tag</tt>.
</td>
</tr>

</table>

<H3>Valid Expressions</H3>

<table border>

<tr>
<th>Name</th><th>Expression</th><th>Return Type</th><th>Description</th>
</tr>

<tr>
<td>Direct Edge Access</td>
<TD><TT>edge(u,v,g)</TT></TD>
<TD><TT>std::pair&lt;edge_descriptor, bool&gt;</TT></TD>
<TD>
Returns a pair consisting of a flag saying whether there exists an
edge between <TT>u</TT> and <TT>v</TT> in graph <TT>g</TT>, and
consisting of the edge descriptor if the edge was found.
</TD>
</TR>
</TABLE>

<H3>Complexity guarantees</H3>

The <TT>edge()</TT> function must return in constant time.


<H3>Models</H3>

<a href="./adjacency_matrix.html"><tt>adjacency_matrix</tt></a>

<H3>Concept Checking Class</H3>

<PRE>
  template &lt;class G&gt;
  struct AdjacencyMatrix
  {
    typedef typename boost::graph_traits&lt;G&gt;::edge_descriptor edge_descriptor;
    void constraints() {
      p = edge(u, v, g);
    }
    typename boost::graph_traits&lt;G&gt;::vertex_descriptor u, v;
    std::pair&lt;bool, edge_descriptor&gt; p;
    G g;
  };
</PRE>


<br>
<HR>
<TABLE>
<TR valign=top>
<TD nowrap>Copyright &copy; 2000-2001</TD><TD>
<A HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</A>, Indiana University (<A HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)
</TD></TR></TABLE>

</BODY>
</HTML>