178 lines
5.5 KiB
Plaintext
178 lines
5.5 KiB
Plaintext
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program chkfft
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! Tests and times one-dimensional FFTs computed by FFTW3
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use, intrinsic :: iso_c_binding
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use FFTW3
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parameter (NMAX=8*1024*1024) !Maximum FFT length
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complex a(NMAX),b(NMAX),c(NMAX)
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real ar(NMAX),br(NMAX),cr(NMAX)
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real mflops
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! integer*8 plan1,plan2 !Pointers to stored plans
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type(C_PTR) :: plan1,plan2 !Pointers to FFTW plans
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character infile*12,arg*8
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logical list
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common/patience/npatience
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equivalence (a,ar),(b,br),(c,cr)
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! include 'fftw3.f90' !FFTW definitions
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nargs=iargc()
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if(nargs.ne.5) then
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print*,'Usage: chkfft3 <nfft | infile> nr nw nc np'
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print*,' nfft: length of FFT'
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print*,' nfft=0: do lengths 2^n, n=2^4 to 2^23'
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print*,' infile: name of file with nfft values, one per line'
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print*,' nr: 0/1 to not read (or read) wisdom'
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print*,' nw: 0/1 to not write (or write) wisdom'
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print*,' nc: 0/1 for real or complex data'
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print*,' np: 0-4 patience for finding best algorithm'
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go to 999
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endif
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list=.false.
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nfft=-1
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call getarg(1,infile)
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open(10,file=infile,status='old',err=1)
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list=.true. !A valid file name was provided
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go to 2
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1 read(infile,*) nfft !Take first argument to be nfft
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2 call getarg(2,arg)
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read(arg,*) nr
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call getarg(3,arg)
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read(arg,*) nw
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call getarg(4,arg)
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read(arg,*) ncomplex
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call getarg(5,arg)
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read(arg,*) npatience
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if(list) write(*,1000) infile,nr,nw,ncomplex,npatience
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1000 format(/'infile: ',a12,' nr:',i2,' nw',i2,' nc:',i2,' np:',i2/)
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if(.not.list) write(*,1002) nfft,nr,nw,ncomplex,npatience
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1002 format(/'nfft: ',i10,' nr:',i2,' nw',i2,' nc:',i2,' np:',i2/)
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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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open(12,file='chkfft.out',status='unknown')
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if(nr.ne.0) then
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isuccess=fftwf_import_wisdom_from_filename('fftwf_wisdom.dat'//char(0))
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if(isuccess.eq.1) then
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write(*,1010)
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1010 format('Imported FFTW wisdom.')
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else
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write(*,1012)
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1012 format('Failed to import FFTW wisdom.')
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go to 999
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endif
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endif
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idum=-1 !Set random seed
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ndim=1 !One-dimensional transforms
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do i=1,NMAX !Set random data
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x=gran()
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y=gran()
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b(i)=cmplx(x,y) !Generate random data
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enddo
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iters=1000000
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if(list .or. (nfft.gt.0)) then
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n1=1
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n2=1
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if(nfft.eq.-1) n2=999999
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write(*,1020)
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1020 format(' NFFT Time rms MHz MFlops iters', &
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' tplan'/61('-'))
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else
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n1=4
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n2=23
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write(*,1030)
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1030 format(' n N=2^n Time rms MHz MFlops iters', &
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' tplan'/63('-'))
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endif
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do ii=n1,n2 !Test one or more FFT lengths
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if(list) then
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read(10,*,end=900) nfft !Read nfft from file
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else if(n2.gt.n1) then
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nfft=2**ii !Do powers of 2
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endif
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iformf=1
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iformb=1
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if(ncomplex.eq.0) then
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iformf=0 !Real-to-complex transform
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iformb=-1 !Complex-to-real (inverse) transform
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endif
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if(nfft.gt.NMAX) go to 900
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a(1:nfft)=b(1:nfft) !Copy test data into a()
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t0=second()
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if(ncomplex.ne.0) then
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plan1=fftwf_plan_dft_1d(nfft,a,c,-1,nflags)
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plan2=fftwf_plan_dft_1d(nfft,a,c,+1,nflags)
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else
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plan1=fftwf_plan_dft_r2c_1d(nfft,ar,c,nflags)
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plan2=fftwf_plan_dft_c2r_1d(nfft,c,ar,nflags)
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endif
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t2=second()
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tplan=t2-t0 !Total planning time for this length
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total=0.
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do iter=1,iters !Now do many iterations
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a(1:nfft)=b(1:nfft) !Copy test data into a()
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t0=second()
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call fftwf_execute_dft(plan1,a,c)
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call fftwf_execute_dft(plan2,c,a)
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t1=second()
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total=total+t1-t0
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if(total.ge.1.0) go to 40 !Cut iterations short if t>1 s
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enddo
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iter=iters
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40 time=0.5*total/iter !Time for one FFT of current length
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tplan=0.5*tplan-time !Planning time for one FFT
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if(tplan.lt.0) tplan=0.
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a(1:nfft)=a(1:nfft)/nfft
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! Compute RMS difference between original array and back-transformed array.
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sq=0.
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if(ncomplex.eq.1) then
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do i=1,nfft
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sq=sq + real(a(i)-b(i))**2 + imag(a(i)-b(i))**2
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enddo
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else
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do i=1,nfft
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sq=sq + (ar(i)-br(i))**2
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enddo
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endif
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rms=sqrt(sq/nfft)
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freq=1.e-6*nfft/time
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mflops=5.0/(1.e6*time/(nfft*log(float(nfft))/log(2.0)))
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if(n2.eq.1 .or. n2.eq.999999) then
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write(*,1050) nfft,time,rms,freq,mflops,iter,tplan
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write(12,1050) nfft,time,rms,freq,mflops,iter,tplan
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1050 format(i8,f11.7,f12.8,f7.2,f8.1,i8,f6.1)
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else
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write(*,1060) ii,nfft,time,rms,freq,mflops,iter,tplan
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write(12,1060) ii,nfft,time,rms,freq,mflops,iter,tplan
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1060 format(i2,i8,f11.7,f12.8,f7.2,f8.1,i8,f6.1)
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endif
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enddo
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900 continue
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if(nw.eq.1) then
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ierr=fftwf_export_wisdom_to_filename('fftwf_wisdom.dat'//char(0))
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write(*,1070)
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1070 format(/'Exported FFTW wisdom')
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endif
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call fftwf_destroy_plan(plan1)
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call fftwf_destroy_plan(plan2)
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999 end program chkfft
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