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            COMPUTES THE FFT   (DOUBLE PRECISION)
            AUTHOR: NUMERICAL RECEIPES, PG. 395
            NN IS THE NUMBER OF DATA: MUST BE A POWER OF 2
            ISIGN=1: DIRECT FT
            ISIGN=-1: INVERSE FT
            DATA IS A COMPLEX ARRAY WITH THE SIGNAL IN INPUT
                                    WITH THE FT IN OUTPUT
            GOOD LUCK, BABY
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SUBROUTINE FFT(DATA,NN,ISIGN)
 
COMMONS: 
 
SUBROUTINES USED:
 
micromap-index
Mon Jul 17 08:57:43 CEST 2017