| 1 | MODULE mod_fft_mathkeisan |
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| 2 | #ifdef FFT_MATHKEISAN |
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| 3 | |
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| 4 | REAL,SAVE,ALLOCATABLE :: Table_forward(:) |
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| 5 | REAL,SAVE,ALLOCATABLE :: Table_backward(:) |
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| 6 | REAL,SAVE :: scale_factor |
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| 7 | INTEGER,SAVE :: vsize |
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| 8 | INTEGER,PARAMETER :: inc=2 |
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| 9 | |
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| 10 | CONTAINS |
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| 11 | |
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| 12 | SUBROUTINE Init_fft(iim,nb_vect_max) |
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| 13 | IMPLICIT NONE |
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| 14 | INTEGER :: iim |
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| 15 | INTEGER :: nb_vect_max |
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| 16 | REAL :: rtmp=1. |
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| 17 | COMPLEX*16 :: ctmp |
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| 18 | INTEGER :: itmp=1 |
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| 19 | INTEGER :: isign=0 |
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| 20 | INTEGER :: ierr |
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| 21 | |
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| 22 | vsize=iim |
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| 23 | scale_factor=1./SQRT(1.*vsize) |
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| 24 | ALLOCATE(Table_forward(2*vsize+64)) |
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| 25 | ALLOCATE(Table_backward(2*vsize+64)) |
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| 26 | |
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| 27 | CALL DZFFTM(isign,vsize,itmp,scale_factor,rtmp,vsize+inc,ctmp,vsize/2+1,table_forward,rtmp,ierr) |
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| 28 | |
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| 29 | CALL ZDFFTM(isign,vsize,itmp,scale_factor,ctmp,vsize/2+1,rtmp,vsize+inc,table_backward,rtmp,ierr) |
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| 30 | |
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| 31 | |
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| 32 | END SUBROUTINE Init_fft |
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| 33 | |
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| 34 | |
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| 35 | SUBROUTINE fft_forward(vect,TF_vect,nb_vect) |
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| 36 | IMPLICIT NONE |
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| 37 | INTEGER,INTENT(IN) :: nb_vect |
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| 38 | REAL,INTENT(IN) :: vect(vsize+inc,nb_vect) |
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| 39 | COMPLEX*16,INTENT(OUT) :: TF_vect(vsize/2+1,nb_vect) |
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| 40 | REAL :: work(4*vsize*nb_vect) |
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| 41 | INTEGER :: ierr |
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| 42 | INTEGER, PARAMETER :: isign=-1 |
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| 43 | |
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| 44 | work=0 |
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| 45 | CALL DZFFTM(isign,vsize,nb_vect,scale_factor,vect,vsize+inc,TF_vect,vsize/2+1,table_forward,work,ierr) |
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| 46 | |
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| 47 | END SUBROUTINE fft_forward |
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| 48 | |
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| 49 | SUBROUTINE fft_backward(TF_vect,vect,nb_vect) |
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| 50 | IMPLICIT NONE |
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| 51 | INTEGER,INTENT(IN) :: nb_vect |
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| 52 | REAL,INTENT(OUT) :: vect(vsize+inc,nb_vect) |
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| 53 | COMPLEX*16,INTENT(IN ) :: TF_vect(vsize/2+1,nb_vect) |
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| 54 | REAL :: work(4*vsize*nb_vect) |
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| 55 | INTEGER :: ierr |
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| 56 | INTEGER, PARAMETER :: isign=1 |
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| 57 | |
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| 58 | work(:)=0 |
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| 59 | CALL ZDFFTM(isign,vsize,nb_vect,scale_factor,TF_vect,vsize/2+1,vect,vsize+inc,table_backward,work,ierr) |
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| 60 | |
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| 61 | END SUBROUTINE fft_backward |
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| 62 | |
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| 63 | #endif |
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| 64 | |
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| 65 | END MODULE mod_fft_mathkeisan |
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| 66 | |
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| 67 | |
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