source: LMDZ4/branches/LMDZ4_AR5/libf/filtrez/mod_fft_fftw.F90 @ 1601

Last change on this file since 1601 was 1601, checked in by Ehouarn Millour, 12 years ago

Updates and upgrades of filter:

  • add minor corrections (r1591 of trunk) in filtreg_mod.F90: some arrays were oversized and the computation of the indexes from which the filter is applied could go wrong in extreme cases.
  • adapt filtreg_p.F (r1597 of trunk) so that BLAS routine DGEMM is only used if 'BLAS' preprocessing flag is set.
  • update FFT filter routines to match current 'trunk' versions (mostly cosmetic changes, exept for the implementation of use of FFTW in mod_fft_fftw.F90).
  • update "arch-PW6_VARGAS.fcm" to enable use of FFTW

NB: implemented FFTs assume working precision to be double precision ; trying to use them when working precision is single precision will clearly end in tragedy.
EM
  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
File size: 3.0 KB
Line 
1!
2! $Id: mod_fft_fftw.F90 1601 2011-12-07 07:05:43Z emillour $
3!
4
5MODULE mod_fft_fftw
6
7#ifdef FFT_FFTW
8
9  REAL, SAVE                   :: scale_factor
10  INTEGER, SAVE                :: vsize
11  INTEGER, PARAMETER           :: inc=1
12 
13  INTEGER*8, ALLOCATABLE, DIMENSION(:), SAVE :: plan_forward
14  INTEGER*8, ALLOCATABLE, DIMENSION(:), SAVE :: plan_backward
15 
16CONTAINS
17 
18  SUBROUTINE Init_fft(iim,nvectmax)
19  IMPLICIT NONE
20#include <fftw3.f>
21    INTEGER :: iim
22    INTEGER :: nvectmax
23
24    INTEGER :: itmp
25
26    INTEGER               :: rank
27    INTEGER               :: howmany
28    INTEGER               :: istride, idist
29    INTEGER               :: ostride, odist
30    INTEGER, DIMENSION(1) :: n_array, inembed, onembed
31
32    REAL,    DIMENSION(iim+1,nvectmax) :: dbidon
33    COMPLEX, DIMENSION(iim/2+1,nvectmax) :: cbidon
34
35    vsize = iim
36    scale_factor = 1./SQRT(1.*vsize)
37
38    dbidon = 0
39    cbidon = 0
40
41    ALLOCATE(plan_forward(nvectmax))
42    ALLOCATE(plan_backward(nvectmax))
43   
44    WRITE(*,*)"!---------------------!"
45    WRITE(*,*)"!                     !"
46    WRITE(*,*)"! INITIALISATION FFTW !"
47    WRITE(*,*)"!                     !"
48    WRITE(*,*)"!---------------------!"
49   
50! On initialise tous les plans
51    DO itmp = 1, nvectmax
52       rank       = 1
53       n_array(1) = iim
54       howmany    = itmp
55       inembed(1) = iim + 1 ; onembed(1) = iim/2 + 1
56       istride    = 1       ; ostride    = 1
57       idist      = iim + 1 ; odist      = iim/2 + 1
58
59       CALL dfftw_plan_many_dft_r2c(plan_forward(itmp), rank, n_array, howmany, &
60            & dbidon, inembed, istride, idist, &
61            & cbidon, onembed, ostride, odist, &
62            & FFTW_ESTIMATE)
63
64       rank       = 1
65       n_array(1) = iim
66       howmany    = itmp
67       inembed(1) = iim/2 + 1 ; onembed(1) = iim + 1
68       istride    = 1         ; ostride    = 1
69       idist      = iim/2 + 1 ; odist      = iim + 1
70       CALL dfftw_plan_many_dft_c2r(plan_backward(itmp), rank, n_array, howmany, &
71            & cbidon, inembed, istride, idist, &
72            & dbidon, onembed, ostride, odist, &
73            & FFTW_ESTIMATE)
74
75    ENDDO
76
77    WRITE(*,*)"!-------------------------!"
78    WRITE(*,*)"!                         !"
79    WRITE(*,*)"! FIN INITIALISATION FFTW !"
80    WRITE(*,*)"!                         !"
81    WRITE(*,*)"!-------------------------!"
82
83  END SUBROUTINE Init_fft
84 
85 
86  SUBROUTINE fft_forward(vect,TF_vect,nb_vect)
87    IMPLICIT NONE
88#include <fftw3.f>
89    INTEGER,INTENT(IN)     :: nb_vect
90    REAL,INTENT(IN)        :: vect(vsize+inc,nb_vect)
91    COMPLEX,INTENT(OUT) :: TF_vect(vsize/2+1,nb_vect)
92
93    CALL dfftw_execute_dft_r2c(plan_forward(nb_vect),vect,TF_vect)
94
95    TF_vect = scale_factor * TF_vect
96
97  END SUBROUTINE fft_forward
98 
99  SUBROUTINE fft_backward(TF_vect,vect,nb_vect)
100    IMPLICIT NONE
101#include <fftw3.f>
102    INTEGER,INTENT(IN)     :: nb_vect
103    REAL,INTENT(OUT)       :: vect(vsize+inc,nb_vect)
104    COMPLEX,INTENT(IN ) :: TF_vect(vsize/2+1,nb_vect)
105
106    CALL dfftw_execute_dft_c2r(plan_backward(nb_vect),TF_vect,vect)
107
108    vect = scale_factor * vect
109
110  END SUBROUTINE fft_backward
111
112#endif
113 
114END MODULE mod_fft_fftw
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