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    <title>cl_khr_fp64</title>
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        <h1>cl_khr_fp64</h1>
        <p>
            Support for <span xmlns="http://www.w3.org/1999/xhtml" class="type">double</span> floating-point precision.
        </p>
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      <div class="refsect2">
        <a id="synopsis"></a>
        <h3>
        </h3>
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                <td align="left">
#pragma OPENCL EXTENSION cl_khr_fp64 : enable
                        </td>
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      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
Support for double floating-point precision is a requirement for a class of scientific computing algorithms/applications. This class of applications can be enabled by adding support for double precision floating-point as an optional extension.
        </p>
        <p>
OpenCL 1.0 adds support for double precision floating-point as an optional extension. An application that wants to use <span class="type">double</span> will need to include the <code class="function">#pragma OPENCL EXTENSION cl_khr_fp64 : enable</code> directive before any double precision data type is declared in the kernel code.
        </p>
        <p>
The lists of built-in <a class="citerefentry" href="scalarDataTypes.html"><span class="citerefentry"><span class="refentrytitle">scalar data types</span></span></a> and <a class="citerefentry" href="vectorDataTypes.html"><span class="citerefentry"><span class="refentrytitle">vector data types</span></span></a> are extended to include the following:
            </p>
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              <tr>
                <th align="left">Type in OpenCL Language</th>
                <th align="left">Description</th>
                <th align="left">API type for application</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td align="left">double</td>
                <td align="left">A double precision vector</td>
                <td align="left">cl_double</td>
              </tr>
              <tr>
                <td align="left">double2</td>
                <td align="left">2-component double vector</td>
                <td align="left">cl_double2</td>
              </tr>
              <tr>
                <td align="left">double4</td>
                <td align="left">4-component double vector</td>
                <td align="left">cl_double4</td>
              </tr>
              <tr>
                <td align="left">double8</td>
                <td align="left">8-component double vector</td>
                <td align="left">cl_double8</td>
              </tr>
              <tr>
                <td align="left">double16</td>
                <td align="left">16-component double vector</td>
                <td align="left">cl_double16</td>
              </tr>
            </tbody>
          </table>
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        <p>
        </p>
        <p>
The double data type must confirm to the IEEE-754 double precision storage format.
        </p>
        <p>
       Conversions from <span class="type">double</span> to <span class="type">half</span> are correctly rounded. Conversions from <span class="type">half</span> to <span class="type">double</span> are lossless.
        </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.x-latest.pdf#page=225" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span>, <a class="citerefentry" href="EXTENSION.html"><span class="citerefentry"><span class="refentrytitle">EXTENSION</span></span></a></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 © 2007-2009 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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