Returns the cross product of p0.xyz and p1.xyz.
          For the form that returns float4, 
          the w component of float4 result returned will be 0.0.
          For the forms that returns half3 or half4, 
          the w component of double result will be 0.0.
        
      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.
          An application that wants to use half
          and halfn
          types will need to include the #pragma OPENCL EXTENSION
          cl_khr_fp16 : enable
          directive.
        
 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.
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.