2009-11-03 19:22:15 -05:00
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subroutine four2a(a,nfft,ndim,isign,iform)
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C IFORM = 1, 0 or -1, as data is
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C complex, real, or the first half of a complex array. Transform
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C values are returned in array DATA. They are complex, real, or
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C the first half of a complex array, as IFORM = 1, -1 or 0.
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C The transform of a real array (IFORM = 0) dimensioned N(1) by N(2)
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C by ... will be returned in the same array, now considered to
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C be complex of dimensions N(1)/2+1 by N(2) by .... Note that if
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C IFORM = 0 or -1, N(1) must be even, and enough room must be
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C reserved. The missing values may be obtained by complex conjuga-
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C tion.
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C The reverse transformation of a half complex array dimensioned
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C N(1)/2+1 by N(2) by ..., is accomplished by setting IFORM
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C to -1. In the N array, N(1) must be the true N(1), not N(1)/2+1.
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C The transform will be real and returned to the input array.
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parameter (NPMAX=100)
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parameter (NSMALL=16384)
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complex a(nfft)
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complex aa(NSMALL)
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integer nn(NPMAX),ns(NPMAX),nf(NPMAX),nl(NPMAX)
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real*8 plan(NPMAX) !Actually should be i*8, but no matter
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data nplan/0/
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include 'fftw3.f'
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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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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)) go to 10
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enddo
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if(nplan.ge.NPMAX) stop 'Too many FFTW plans requested.'
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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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C Planning: FFTW_ESTIMATE, FFTW_ESTIMATE_PATIENT, FFTW_MEASURE,
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C FFTW_PATIENT, FFTW_EXHAUSTIVE
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C NB: "EXHAUSTIVE" takes more or less forever, for long transforms.
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npatience=1
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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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do j=1,jz
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aa(j)=a(j)
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enddo
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endif
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call sleep_msec(0)
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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,
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+ 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,
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+ 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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call sleep_msec(0)
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i=nplan
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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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do j=1,jz
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a(j)=aa(j)
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enddo
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endif
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10 continue
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call sleep_msec(0)
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call sfftw_execute_(plan(i))
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call sleep_msec(0)
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return
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999 do i=1,nplan
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call sfftw_destroy_plan_(plan(i))
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enddo
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return
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end
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