Matrix size  FFT time (ms)  Normalized error

           4         1.1110  0.681690113816209 
           8         0.0860  0.283802756086470 
          16         0.1070  0.104753445108088 
          32         0.2430  0.040096749477005 
          64         0.6390  0.015508155295736 
         128         2.3400  0.005385667866781 
         256         8.9350  0.001924734456330 
         512        35.8060  0.000951747932886 
        1024       147.5090  0.000288416313164 
        2048       593.3840  0.000109025932857 
        4096      2497.4940  0.000038526063940