165 lines
5.2 KiB
Plaintext
165 lines
5.2 KiB
Plaintext
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program chkfft
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! Tests and times one-dimensional FFTs computed by four2a().
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! An all-Fortran version of four2a() is available, but the preferred
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! version uses calls to the FFTW library.
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parameter (NMAX=8*1024*1024) !Maximum FFT length
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complex a(NMAX),b(NMAX)
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real ar(NMAX),br(NMAX)
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real mflops
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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)
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nargs=iargc()
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if(nargs.ne.5) then
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print*,'Usage: chkfft <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 !Takje 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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call sgran()
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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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open(12,file='chkfft.out',status='unknown')
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open(13,file='fftwf_wisdom.dat',status='unknown')
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if(nr.ne.0) then
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call import_wisdom_from_file(isuccess,13)
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if(isuccess.eq.0) then
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write(*,1010)
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1010 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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call four2a(a,nfft,ndim,-1,iformf) !Get planning time for forward FFT
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call four2a(a,nfft,ndim,+1,iformb) !Get planning time for backward FFT
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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 four2a(a,nfft,ndim,-1,iformf) !Forward FFT
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call four2a(a,nfft,ndim,+1,iformb) !Backward FFT on same data
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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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if(mod(ii,50).eq.0) call four2a(0,-1,0,0,0)
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enddo
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900 continue
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if(nw.eq.1) then
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rewind 13
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call export_wisdom_to_file(13)
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! write(*,1070)
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!1070 format(/'Exported FFTW wisdom')
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endif
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999 call four2a(0,-1,0,0,0)
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end program chkfft
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