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    <title>fast_normalize</title>
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    <div class="refentry">
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      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="fast_normalize"></a>
        <h1>fast_normalize</h1>
        <p>
            Normal vector length 1.
        </p>
      </div>
      <div class="refsynopsisdiv">
        <h2></h2>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
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              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef">
                    <a class="link" href="vectorDataTypes.html" target="_top">float<em class="replaceable"><code>n</code></em></a>
                    <strong class="fsfunc">                   
                        fast_normalize
                    </strong>
                (</code>
                <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="vectorDataTypes.html" target="_top">float<em class="replaceable"><code>n</code></em></a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">p</var><code>)</code></td>
              </td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
        Returns a vector in the same direction as <code class="varname">p</code> but with a length of 1. <code class="function">fast_normalize</code> is computed as:
</p>
        <div class="literallayout">
          <p>          <code class="varname">p</code> * <a class="citerefentry" href="sqrt.html"><span class="citerefentry"><span class="refentrytitle">half_sqrt</span></span></a>(<code class="varname">p.x</code><sup>2</sup> + <code class="varname">p.y</code><sup>2</sup> +...)</p>
        </div>
        <p>
        </p>
        <p>
        The result shall be within 8192 ulps error from the infinitely precise result of:
</p>
        <div class="literallayout">
          <p>          if ( <a class="citerefentry" href="any.html"><span class="citerefentry"><span class="refentrytitle">all</span></span></a>(<code class="varname">p</code> == 0.0f))<br />
                    <code class="varname">result = p</code>;<br />
          else<br />
                    <code class="varname">result = p</code> /  <a class="citerefentry" href="sqrt.html"><span class="citerefentry"><span class="refentrytitle">sqrt</span></span></a>(<code class="varname">p.x</code><sup>2</sup> + <code class="varname">p.y</code><sup>2</sup> +...);</p>
        </div>
        <p>
        </p>
        <p>
    with the following exceptions:
        </p>
        <div class="orderedlist">
          <ol class="orderedlist" type="1">
            <li class="listitem">If the sum of squares is greater than FLT_MAX then the value of the floating-point values in the result vector are undefined.</li>
            <li class="listitem">If the sum of squares is less than FLT_MIN then the implementation may return back <code class="varname">p</code>.</li>
            <li class="listitem">If the device is in 'denorms are flushed to zero' mode, individual operand elements with magnitude less than <a class="citerefentry" href="sqrt.html"><span class="citerefentry"><span class="refentrytitle">sqrt</span></span></a>(FLT_MIN) may be flushed to zero before proceeding with the calculation.</li>
          </ol>
        </div>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
            Built-in geometric functions operate component-wise and the description is per-component. 
            The type name <span class="type">float</span><em class="replaceable"><code>n</code></em> indicates that the function can take <span class="type">float</span>, 
            <span class="type">float2</span>, <span class="type">float3</span>, or <span class="type">float4</span> as the type 
            for the arguments.
        </p>
        <p>
            The built-in geometric functions are implemented using the round to nearest even rounding mode.
        </p>
        <p>
            The geometric functions can be implemented using contractions such as
            <a class="citerefentry" href="mad.html"><span class="citerefentry"><span class="refentrytitle">mad</span></span></a> or 
            <a class="citerefentry" href="fma.html"><span class="citerefentry"><span class="refentrytitle">fma</span></span></a>.
        </p>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />
                                                 
            <a href="http://www.khronos.org/registry/cl/specs/opencl-1.1.pdf#page=216" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="geometricFunctions.html"><span class="citerefentry"><span class="refentrytitle">Geometric Functions</span></span></a> 
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2010 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be included
in all copies or substantial portions of the Materials.
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