Built-in geometric functions operate component-wise. The description
      is per-component. floatn is
      float, float2, float3, or float4 and
      doublen is double, double2,
      double3, or double4. The built-in geometric functions are
      implemented using the round to nearest even rounding mode.
    
The geometric functions can be implemented using contractions such as mad or fma.
 Copyright © 2007-2013 The Khronos Group Inc. 
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copy of this software and/or associated documentation files (the
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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.
Copyright © 2007-2013 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.