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115 lines
3.6 KiB
Fortran
115 lines
3.6 KiB
Fortran
subroutine four2a(a,nfft,ndim,isign,iform)
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! IFORM = 1, 0 or -1, as data is
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! complex, real, or the first half of a complex array. Transform
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! values are returned in array DATA. They are complex, real, or
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! the first half of a complex array, as IFORM = 1, -1 or 0.
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! The transform of a real array (IFORM = 0) dimensioned N(1) by N(2)
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! by ... will be returned in the same array, now considered to
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! be complex of dimensions N(1)/2+1 by N(2) by .... Note that if
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! IFORM = 0 or -1, N(1) must be even, and enough room must be
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! reserved. The missing values may be obtained by complex conjugation.
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! The reverse transformation of a half complex array dimensioned
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! N(1)/2+1 by N(2) by ..., is accomplished by setting IFORM
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! to -1. In the N array, N(1) must be the true N(1), not N(1)/2+1.
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! The transform will be real and returned to the input array.
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! This version of four2a makes calls to the FFTW library to do the
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! actual computations.
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use fftw3
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parameter (NPMAX=2100) !Max numberf of stored plans
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parameter (NSMALL=16384) !Max size of "small" FFTs
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complex a(nfft) !Array to be transformed
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complex aa(NSMALL) !Local copy of "small" a()
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integer nn(NPMAX),ns(NPMAX),nf(NPMAX) !Params of stored plans
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integer*8 nl(NPMAX),nloc !More params of plans
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integer*8 plan(NPMAX) !Pointers to stored plans
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logical found_plan
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data nplan/0/ !Number of stored plans
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common/patience/npatience,nthreads !Patience and threads for FFTW plans
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save plan,nplan,nn,ns,nf,nl
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if(nfft.lt.0) go to 999
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nloc=loc(a)
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found_plan = .false.
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!$omp critical(four2a_setup)
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do i=1,nplan
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if(nfft.eq.nn(i) .and. isign.eq.ns(i) .and. &
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iform.eq.nf(i) .and. nloc.eq.nl(i)) then
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found_plan = .true.
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exit
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end if
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enddo
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if(i.ge.NPMAX) stop 'Too many FFTW plans requested.'
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if (.not. found_plan) then
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nplan=nplan+1
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i=nplan
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nn(i)=nfft
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ns(i)=isign
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nf(i)=iform
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nl(i)=nloc
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! Planning: FFTW_ESTIMATE, FFTW_ESTIMATE_PATIENT, FFTW_MEASURE,
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! FFTW_PATIENT, FFTW_EXHAUSTIVE
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nflags=FFTW_ESTIMATE
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if(npatience.eq.1) nflags=FFTW_ESTIMATE_PATIENT
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if(npatience.eq.2) nflags=FFTW_MEASURE
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if(npatience.eq.3) nflags=FFTW_PATIENT
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if(npatience.eq.4) nflags=FFTW_EXHAUSTIVE
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if(nfft.le.NSMALL) then
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jz=nfft
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if(iform.eq.0) jz=nfft/2
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aa(1:jz)=a(1:jz)
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endif
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!$omp critical(fftw) ! serialize non thread-safe FFTW3 calls
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if(isign.eq.-1 .and. iform.eq.1) then
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call sfftw_plan_dft_1d(plan(i),nfft,a,a,FFTW_FORWARD,nflags)
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else if(isign.eq.1 .and. iform.eq.1) then
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call sfftw_plan_dft_1d(plan(i),nfft,a,a,FFTW_BACKWARD,nflags)
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else if(isign.eq.-1 .and. iform.eq.0) then
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call sfftw_plan_dft_r2c_1d(plan(i),nfft,a,a,nflags)
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else if(isign.eq.1 .and. iform.eq.-1) then
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call sfftw_plan_dft_c2r_1d(plan(i),nfft,a,a,nflags)
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else
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stop 'Unsupported request in four2a'
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endif
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!$omp end critical(fftw)
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if(nfft.le.NSMALL) then
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jz=nfft
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if(iform.eq.0) jz=nfft/2
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a(1:jz)=aa(1:jz)
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endif
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end if
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!$omp end critical(four2a_setup)
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call sfftw_execute(plan(i))
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return
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999 continue
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!$omp critical(four2a)
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do i=1,nplan
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! The test is only to silence a compiler warning:
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if(ndim.ne.-999) then
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!$omp critical(fftw) ! serialize non thread-safe FFTW3 calls
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call sfftw_destroy_plan(plan(i))
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!$omp end critical(fftw)
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end if
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enddo
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nplan=0
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!$omp end critical(four2a)
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return
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end subroutine four2a
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