142 lines
4.3 KiB
Plaintext
142 lines
4.3 KiB
Plaintext
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program timefft
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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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complex(C_FLOAT_COMPLEX),pointer :: a(:),b(:),c(:)
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real(C_FLOAT),pointer :: ar(:),br(:)
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type(C_PTR) :: plan1,plan2 !Pointers to FFTW plans
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type(C_PTR) :: pa,pb,pc
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integer(C_INT) iret
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integer*8 count0,count1,clkfreq
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character problem*9
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logical linplace,lcomplex,lthreading
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! Get command-line parameters
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call timefft_opts(npatience,maxthreads,linplace,lcomplex,nfft,problem,nflags)
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lthreading=maxthreads.ge.1
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maxthreads=max(1,maxthreads)
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call sgran() ! see C rand generator (used in gran)
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! Allocate data arrays
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pa=fftwf_alloc_complex(int(nfft,C_SIZE_T))
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call c_f_pointer(pa,a,[nfft])
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call c_f_pointer(pa,ar,[nfft])
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pb=fftwf_alloc_complex(int(nfft,C_SIZE_T))
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call c_f_pointer(pb,b,[nfft])
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call c_f_pointer(pb,br,[nfft])
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pc=fftwf_alloc_complex(int(nfft,C_SIZE_T))
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call c_f_pointer(pc,c,[nfft])
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! Initialize FFTW threading
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if(lthreading) iret=fftwf_init_threads()
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! Import FFTW wisdom, if available
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iret=fftwf_import_wisdom_from_filename(C_CHAR_'wis.dat' // C_NULL_CHAR)
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do i=1,nfft !Generate random data
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x=gran()
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y=gran()
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b(i)=cmplx(x,y)
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enddo
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iters=100
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write(*,1000)
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1000 format(/'Problem Threads Plan Time Gflops RMS iters'/ &
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'--------------------------------------------------------')
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! Try nthreads = 1,maxthreads
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do nthreads=1,maxthreads
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a(1:nfft)=b(1:nfft) !Copy test data into a()
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call system_clock(count0,clkfreq)
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! Make the plans
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if(lthreading) call fftwf_plan_with_nthreads(nthreads)
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if(lcomplex) then
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if(linplace) then
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plan1=fftwf_plan_dft_1d(nfft,a,a,-1,nflags)
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plan2=fftwf_plan_dft_1d(nfft,a,a,+1,nflags)
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else
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plan1=fftwf_plan_dft_1d(nfft,a,c,-1,nflags)
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plan2=fftwf_plan_dft_1d(nfft,c,a,+1,nflags)
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endif
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else
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if(linplace) then
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plan1=fftwf_plan_dft_r2c_1d(nfft,ar,a,nflags)
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plan2=fftwf_plan_dft_c2r_1d(nfft,a,ar,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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endif
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call system_clock(count1,clkfreq)
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tplan=0.5*float(count1-count0)/float(clkfreq) !Plan time for one transform
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total=0.
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do iter=1,iters !Do many iterations
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a=b !Copy test data into a()
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call system_clock(count0,clkfreq)
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! Compute the transforms
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if(lcomplex) then
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if(linplace) then
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call fftwf_execute_dft(plan1,a,a)
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call fftwf_execute_dft(plan2,a,a)
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else
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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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endif
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else
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if(linplace) then
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call fftwf_execute_dft_r2c(plan1,ar,a)
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call fftwf_execute_dft_c2r(plan2,a,ar)
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else
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call fftwf_execute_dft_r2c(plan1,ar,c)
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call fftwf_execute_dft_c2r(plan2,c,ar)
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endif
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endif
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call system_clock(count1,clkfreq)
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total=total + float(count1-count0)/float(clkfreq)
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if(total>=1.0 .and. iter>=10) go to 40 !Cut iterations short ?
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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
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gflops=5.0/(1.e9*time/(nfft*log(float(nfft))/log(2.0)))
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a(1:nfft)=a(1:nfft)/nfft !Normalize the back-transformed data
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! Compute RMS difference between original data and back-transformed data.
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sq=0.
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if(lcomplex) then
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do i=1,nfft
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sq=sq + real(a(i)-b(i))**2 + aimag(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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! Display results
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write(*,1050) problem,nthreads,tplan,time,gflops,rms,iter
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1050 format(a9,i4,f8.3,f10.6,f7.2,f11.7,i5)
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enddo
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! Export accumulated FFTW wisdom
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iret=fftwf_export_wisdom_to_filename(C_CHAR_'wis.dat' // C_NULL_CHAR)
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! Clean up
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call fftwf_destroy_plan(plan1)
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call fftwf_destroy_plan(plan2)
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call fftwf_free(pa)
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call fftwf_free(pb)
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call fftwf_free(pc)
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call fftwf_cleanup_threads()
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call fftwf_cleanup()
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end program timefft
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