1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>dot_product</title> 5<link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../index.html" title="Chapter 1. Geometry"> 8<link rel="up" href="../arithmetic.html" title="Arithmetic"> 9<link rel="prev" href="divide_value.html" title="divide_value"> 10<link rel="next" href="multiply_point.html" title="multiply_point"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="divide_value.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../arithmetic.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="multiply_point.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="geometry.reference.arithmetic.dot_product"></a><a class="link" href="dot_product.html" title="dot_product">dot_product</a> 28</h4></div></div></div> 29<p> 30 <a class="indexterm" name="idm45635685709936"></a> 31Computes the dot product (or scalar product) of 2 vectors (points). 32 </p> 33<h6> 34<a name="geometry.reference.arithmetic.dot_product.h0"></a> 35 <span class="phrase"><a name="geometry.reference.arithmetic.dot_product.synopsis"></a></span><a class="link" href="dot_product.html#geometry.reference.arithmetic.dot_product.synopsis">Synopsis</a> 36 </h6> 37<p> 38</p> 39<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Point1</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Point2</span><span class="special">></span> 40<span class="identifier">select_coordinate_type</span><span class="special"><</span><span class="identifier">Point1</span><span class="special">,</span> <span class="identifier">Point2</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">dot_product</span><span class="special">(</span><span class="identifier">Point1</span> <span class="keyword">const</span> <span class="special">&</span> <span class="identifier">p1</span><span class="special">,</span> <span class="identifier">Point2</span> <span class="keyword">const</span> <span class="special">&</span> <span class="identifier">p2</span><span class="special">)</span></pre> 41<p> 42 </p> 43<h6> 44<a name="geometry.reference.arithmetic.dot_product.h1"></a> 45 <span class="phrase"><a name="geometry.reference.arithmetic.dot_product.parameters"></a></span><a class="link" href="dot_product.html#geometry.reference.arithmetic.dot_product.parameters">Parameters</a> 46 </h6> 47<div class="informaltable"><table class="table"> 48<colgroup> 49<col> 50<col> 51<col> 52<col> 53</colgroup> 54<thead><tr> 55<th> 56 <p> 57 Type 58 </p> 59 </th> 60<th> 61 <p> 62 Concept 63 </p> 64 </th> 65<th> 66 <p> 67 Name 68 </p> 69 </th> 70<th> 71 <p> 72 Description 73 </p> 74 </th> 75</tr></thead> 76<tbody> 77<tr> 78<td> 79 <p> 80 Point1 const & 81 </p> 82 </td> 83<td> 84 <p> 85 Any type fulfilling a Point Concept 86 </p> 87 </td> 88<td> 89 <p> 90 p1 91 </p> 92 </td> 93<td> 94 <p> 95 first point 96 </p> 97 </td> 98</tr> 99<tr> 100<td> 101 <p> 102 Point2 const & 103 </p> 104 </td> 105<td> 106 <p> 107 Any type fulfilling a Point Concept 108 </p> 109 </td> 110<td> 111 <p> 112 p2 113 </p> 114 </td> 115<td> 116 <p> 117 second point 118 </p> 119 </td> 120</tr> 121</tbody> 122</table></div> 123<h6> 124<a name="geometry.reference.arithmetic.dot_product.h2"></a> 125 <span class="phrase"><a name="geometry.reference.arithmetic.dot_product.returns"></a></span><a class="link" href="dot_product.html#geometry.reference.arithmetic.dot_product.returns">Returns</a> 126 </h6> 127<p> 128 the dot product 129 </p> 130<h6> 131<a name="geometry.reference.arithmetic.dot_product.h3"></a> 132 <span class="phrase"><a name="geometry.reference.arithmetic.dot_product.header"></a></span><a class="link" href="dot_product.html#geometry.reference.arithmetic.dot_product.header">Header</a> 133 </h6> 134<p> 135 Either 136 </p> 137<p> 138 <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> 139 </p> 140<p> 141 Or 142 </p> 143<p> 144 <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">arithmetic</span><span class="special">/</span><span class="identifier">dot_product</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> 145 </p> 146<h6> 147<a name="geometry.reference.arithmetic.dot_product.h4"></a> 148 <span class="phrase"><a name="geometry.reference.arithmetic.dot_product.examples"></a></span><a class="link" href="dot_product.html#geometry.reference.arithmetic.dot_product.examples">Examples</a> 149 </h6> 150<p> 151 Calculate the dot product of two points 152 </p> 153<p> 154</p> 155<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 156 157<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 158<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">arithmetic</span><span class="special">/</span><span class="identifier">dot_product</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 159<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">adapted</span><span class="special">/</span><span class="identifier">boost_array</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 160 161<span class="keyword">namespace</span> <span class="identifier">bg</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">;</span> <a class="co" name="geometry.reference.arithmetic.dot_product.c0" href="dot_product.html#geometry.reference.arithmetic.dot_product.c1"><img src="../../../../../../../doc/src/images/callouts/1.png" alt="1" border="0"></a> 162 163<span class="identifier">BOOST_GEOMETRY_REGISTER_BOOST_ARRAY_CS</span><span class="special">(</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">)</span> 164 165 166<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> 167<span class="special">{</span> 168 <span class="keyword">double</span> <span class="identifier">dp1</span><span class="special">,</span><span class="identifier">dp2</span><span class="special">,</span><span class="identifier">dp3</span><span class="special">,</span><span class="identifier">dp4</span><span class="special">;</span> 169 <span class="identifier">bg</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">point</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="number">3</span><span class="special">,</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">></span> <span class="identifier">point1</span><span class="special">(</span><span class="number">1.0</span><span class="special">,</span> <span class="number">2.0</span><span class="special">,</span> <span class="number">3.0</span><span class="special">);</span> 170 <span class="identifier">bg</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">point</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="number">3</span><span class="special">,</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">></span> <span class="identifier">point2</span><span class="special">(</span><span class="number">4.0</span><span class="special">,</span> <span class="number">5.0</span><span class="special">,</span> <span class="number">6.0</span><span class="special">);</span> 171 172 <span class="comment">//Example 1</span> 173 <span class="identifier">dp1</span> <span class="special">=</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">dot_product</span><span class="special">(</span><span class="identifier">point1</span><span class="special">,</span> <span class="identifier">point2</span><span class="special">);</span> 174 175 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Dot Product 1: "</span><span class="special"><<</span> <span class="identifier">dp1</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> 176 177 <span class="identifier">bg</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">point</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="number">2</span><span class="special">,</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">></span> <span class="identifier">point3</span><span class="special">(</span><span class="number">3.0</span><span class="special">,</span> <span class="number">2.0</span><span class="special">);</span> 178 <span class="identifier">bg</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">point</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="number">2</span><span class="special">,</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">></span> <span class="identifier">point4</span><span class="special">(</span><span class="number">4.0</span><span class="special">,</span> <span class="number">7.0</span><span class="special">);</span> 179 180 <span class="comment">//Example 2 </span> 181 <span class="identifier">dp2</span> <span class="special">=</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">dot_product</span><span class="special">(</span><span class="identifier">point3</span><span class="special">,</span> <span class="identifier">point4</span><span class="special">);</span> 182 183 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Dot Product 2: "</span><span class="special"><<</span> <span class="identifier">dp2</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> 184 185 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="number">2</span><span class="special">></span> <span class="identifier">a</span> <span class="special">=</span> <span class="special">{</span><span class="number">1</span><span class="special">,</span> <span class="number">2</span><span class="special">};</span> 186 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="number">2</span><span class="special">></span> <span class="identifier">b</span> <span class="special">=</span> <span class="special">{</span><span class="number">2</span><span class="special">,</span> <span class="number">3</span><span class="special">};</span> 187 188 <span class="comment">//Example 3</span> 189 <span class="identifier">dp3</span> <span class="special">=</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">dot_product</span><span class="special">(</span><span class="identifier">a</span><span class="special">,</span> <span class="identifier">b</span><span class="special">);</span> 190 191 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Dot Product 3: "</span><span class="special"><<</span> <span class="identifier">dp3</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> 192 193 <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> 194 195<span class="special">}</span> 196</pre> 197<p> 198 </p> 199<div class="calloutlist"><table border="0" summary="Callout list"><tr> 200<td width="5%" valign="top" align="left"><p><a name="geometry.reference.arithmetic.dot_product.c1"></a><a href="#geometry.reference.arithmetic.dot_product.c0"><img src="../../../../../../../doc/src/images/callouts/1.png" alt="1" border="0"></a> </p></td> 201<td valign="top" align="left"><p> 202 Convenient namespace alias 203 </p></td> 204</tr></table></div> 205<p> 206 Output: 207 </p> 208<pre class="programlisting">Dot Product 1: 32 209Dot Product 2: 26 210Dot Product 3: 8 211</pre> 212</div> 213<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 214<td align="left"></td> 215<td align="right"><div class="copyright-footer">Copyright © 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam 216 Wulkiewicz, Oracle and/or its affiliates<p> 217 Distributed under the Boost Software License, Version 1.0. (See accompanying 218 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 219 </p> 220</div></td> 221</tr></table> 222<hr> 223<div class="spirit-nav"> 224<a accesskey="p" href="divide_value.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../arithmetic.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="multiply_point.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 225</div> 226</body> 227</html> 228
