Added and updated documentation of correct, transform, distance, comparable_distance

[SVN r71153]

doc/src/examples/algorithms/comparable_distance.cpp

@@ -0,0 +1,66 @@
+// Boost.Geometry (aka GGL, Generic Geometry Library)
+// QuickBook Example
+
+// Copyright (c) 2011 Barend Gehrels, Amsterdam, the Netherlands.
+
+// Use, modification and distribution is subject to 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)
+
+//[comparable_distance
+//` Shows how to efficiently get the closest point
+
+#include <iostream>
+
+#include <boost/geometry/geometry.hpp>
+
+#include <boost/numeric/conversion/bounds.hpp>
+#include <boost/foreach.hpp>
+
+int main()
+{
+    typedef boost::geometry::model::d2::point_xy<double> point_type;
+    
+    point_type p(1.4, 2.6);
+    
+    std::vector<point_type> v;
+    for (double x = 0.0; x <= 4.0; x++)
+    {
+        for (double y = 0.0; y <= 4.0; y++)
+        {
+            v.push_back(point_type(x, y));
+        }
+    }
+    
+    point_type min_p;
+    double min_d = boost::numeric::bounds<double>::highest();
+    BOOST_FOREACH(point_type const& pv, v)
+    {
+        double d = boost::geometry::comparable_distance(p, pv);
+        if (d < min_d)
+        {
+            min_d = d;
+            min_p = pv;
+        }
+    }
+    
+    std::cout 
+        << "Closest: " << boost::geometry::dsv(minp) << std::endl
+        << "At: " << boost::geometry::distance(p, minp) << std::endl;
+
+    return 0;
+}
+
+//]
+
+
+//[comparable_distance_output
+/*`
+Output:
+[pre
+Closest: (1, 3)
+At: 0.565685
+]
+*/
+//]
+