atan2

Testing different implementation of Atan2

reference std implementation time: 0.315573

nvidia implementation time: 0.0226615

AVG error 1.21485e-06
Max error 3.51667e-06

cern implementation time: 0.192172

AVG error 2.38482e-08
Max error 2.38419e-07

fast implementation time: 0.00930621

AVG error 9.82156e-06
Max error 2.76566e-05

approx implementation time: 0.0960178

AVG error 0.00312734
Max error 0.00495219