FFT
  FORTRAN90 version
 
  Demonstrate an implementation of the Fast Fourier Transform
  of a complex data vector.
 
  Accuracy check:
 
    FFT ( FFT ( X(1:N) ) ) == N * X(1:N)
 
             N    Error         Time              MFLOPS
 
             2    0.1317E-08    0.2552E-04    0.3919    
             4    0.2356E-07    0.5543E-04    0.7217    
             8    0.4724E-07    0.7947E-04     1.510    
            16    0.7709E-07    0.1096E-03     2.921    
            32    0.9137E-07    0.1489E-03     5.374    
            64    0.7309E-07    0.1839E-03     10.44    
           128    0.8039E-07    0.2263E-03     19.80    
           256    0.1115E-06    0.2904E-03     35.26    
           512    0.9606E-07    0.3594E-03     64.10    
          1024    0.1212E-06    0.4919E-03     104.1    
          2048    0.1307E-06    0.6921E-03     162.7    
          4096    0.1383E-06    0.1286E-02     191.1    
          8192    0.1369E-06    0.2406E-02     221.3    
         16384    0.1440E-06    0.4584E-02     250.2    
         32768    0.1524E-06    0.8873E-02     277.0    
         65536    0.1627E-06    0.1838E-01     285.3    
        131072    0.1687E-06    0.2711E-01     410.9    
        262144    0.1732E-06    0.6354E-01     371.3    
        524288    0.1708E-06    0.9718E-01     512.5    
       1048576    0.1801E-06    0.2104         498.4    
 
FFT:
  Normal end of execution.