Provided by: opencl-1.2-man-doc_1.0~svn22836-1.1_all
fast_normalize - Normal vector length 1. floatn fast_normalize(floatn p);
Returns a vector in the same direction as p but with a length of 1. fast_normalize is computed as: p * sqrt(3clc)(p.x2 + p.y2 +...) The result shall be within 8192 ulps error from the infinitely precise result of: if ( any(3clc)(p == 0.0f)) result = p; else result = p / sqrt(3clc)(p.x2 + p.y2 +...); with the following exceptions: 1. If the sum of squares is greater than FLT_MAX then the value of the floating-point values in the result vector are undefined. 2. If the sum of squares is less than FLT_MIN then the implementation may return back p. 3. If the device is in 'denorms are flushed to zero' mode, individual operand elements with magnitude less than sqrt(3clc)(FLT_MIN) may be flushed to zero before proceeding with the calculation.
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(3clc) or fma(3clc).
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1. OpenCL Specification page 262, section 6.12.5 - Geometric Functions