Add chkfft.f90; more thorough comments in four2a.f90.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4835 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Joe Taylor 2014-12-18 16:41:18 +00:00
parent cfec462e73
commit 22e15084e1
4 changed files with 196 additions and 28 deletions

157
lib/chkfft.f90 Normal file
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@ -0,0 +1,157 @@
program chkfft
! Tests and times one-dimensional FFTs computed by four2a().
! An all-Fortran version of four2a() is available, but the preferred
! version uses calls to the FFTW library.
parameter (NMAX=8*1024*1024) !Maximum FFT length
complex a(NMAX),b(NMAX)
real ar(NMAX),br(NMAX)
real mflops
character infile*12,arg*8
logical list
common/patience/npatience
equivalence (a,ar),(b,br)
nargs=iargc()
if(nargs.ne.5) then
print*,'Usage: chkfft <nfft | infile> nr nw nc np'
print*,' nr: 0/1 for read wisdom'
print*,' nw: 0/1 for write wisdom'
print*,' nc: 0/1 for real/complex'
print*,' np: patience, 0-4'
print*,' negative nfft: powers of 2 up to 2^(-nfft)'
go to 999
endif
list=.false.
nfft=0
call getarg(1,infile)
open(10,file=infile,status='old',err=1)
list=.true. !A valid file name was provided
go to 2
1 read(infile,*) nfft !Takje first argument to be nfft
2 call getarg(2,arg)
read(arg,*) nr
call getarg(3,arg)
read(arg,*) nw
call getarg(4,arg)
read(arg,*) ncomplex
call getarg(5,arg)
read(arg,*) npatience
if(list) write(*,1000) infile,nr,nw,ncomplex,npatience
1000 format(/'infile: ',a12,' nr:',i2,' nw',i2,' nc:',i2,' np:',i2/)
if(.not.list) write(*,1002) nfft,nr,nw,ncomplex,npatience
1002 format(/'nfft: ',i10,' nr:',i2,' nw',i2,' nc:',i2,' np:',i2/)
open(12,file='chkfft.out',status='unknown')
open(13,file='fftw_wisdom.dat',status='unknown')
if(nr.ne.0) then
call import_wisdom_from_file(isuccess,13)
if(isuccess.ne.0) write(*,1010)
1010 format('Imported FFTW wisdom')
endif
idum=-1 !Set random seed
ndim=1 !One-dimensional transforms
do i=1,NMAX !Set random data
x=gran()
y=gran()
b(i)=cmplx(x,y) !Generate random data
enddo
iters=1000000
if(list .or. (nfft.gt.0)) then
n1=1
n2=1
if(nfft.eq.0) n2=999999
write(*,1020)
1020 format(' NFFT Time rms MHz MFlops iters', &
' tplan'/61('-'))
else
n1=4
n2=min(-nfft,23)
write(*,1030)
1030 format(' n N=2^n Time rms MHz MFlops iters', &
' tplan'/63('-'))
endif
do ii=n1,n2 !Test one or more FFT lengths
if(list) then
read(10,*,end=900) nfft !Read nfft from file
else if(n2.gt.n1) then
nfft=2**ii !Do powers of 2
endif
iformf=1
iformb=1
if(ncomplex.eq.0) then
iformf=0 !Real-to-complex transform
iformb=-1 !Complex-to-real (inverse) transform
endif
if(nfft.gt.NMAX) go to 900
a(1:nfft)=b(1:nfft) !Copy test data into a()
t0=second()
call four2a(a,nfft,ndim,-1,iformf) !Get planning time for forward FFT
call four2a(a,nfft,ndim,+1,iformb) !Get planning time for backward FFT
t2=second()
tplan=t2-t0 !Total planning time for this length
total=0.
do iter=1,iters !Now do many iterations
a(1:nfft)=b(1:nfft) !Copy test data into a()
t0=second()
call four2a(a,nfft,ndim,-1,iformf) !Forward FFT
call four2a(a,nfft,ndim,+1,iformb) !Backward FFT on same data
t1=second()
total=total+t1-t0
if(total.ge.1.0) go to 40 !Cut iterations short if t>1 s
enddo
iter=iters
40 time=0.5*total/iter !Time for one FFT of current length
tplan=0.5*tplan-time !Planning time for one FFT
if(tplan.lt.0) tplan=0.
a(1:nfft)=a(1:nfft)/nfft
! Compute RMS error
sq=0.
if(ncomplex.eq.1) then
do i=1,nfft
sq=sq + real(a(i)-b(i))**2 + imag(a(i)-b(i))**2
enddo
else
do i=1,nfft
sq=sq + (ar(i)-br(i))**2
enddo
endif
rms=sqrt(sq/nfft)
freq=1.e-6*nfft/time
mflops=5.0/(1.e6*time/(nfft*log(float(nfft))/log(2.0)))
if(n2.eq.999999) then
write(*,1050) nfft,time,rms,freq,mflops,iter,tplan
write(12,1050) nfft,time,rms,freq,mflops,iter,tplan
1050 format(i8,f11.7,f12.8,f7.2,f8.1,i8,f6.1)
else
write(*,1060) ii,nfft,time,rms,freq,mflops,iter,tplan
write(12,1060) ii,nfft,time,rms,freq,mflops,iter,tplan
1060 format(i2,i8,f11.7,f12.8,f7.2,f8.1,i8,f6.1)
endif
if(mod(ii,50).eq.0) call four2a(0,-1,0,0,0)
enddo
900 continue
if(nw.eq.1) then
rewind 13
call export_wisdom_to_file(13)
write(*,1070)
1070 format('Exported FFTW wisdom')
endif
999 call four2a(0,-1,0,0,0)
end program chkfft

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@ -1,30 +1,34 @@
subroutine four2a(a,nfft,ndim,isign,iform)
! IFORM = 1, 0 or -1, as data is
! complex, real, or the first half of a complex array. Transform
! values are returned in array DATA. They are complex, real, or
! the first half of a complex array, as IFORM = 1, -1 or 0.
! IFORM = 1, 0 or -1, as data is
! complex, real, or the first half of a complex array. Transform
! values are returned in array DATA. They are complex, real, or
! the first half of a complex array, as IFORM = 1, -1 or 0.
! The transform of a real array (IFORM = 0) dimensioned N(1) by N(2)
! by ... will be returned in the same array, now considered to
! be complex of dimensions N(1)/2+1 by N(2) by .... Note that if
! IFORM = 0 or -1, N(1) must be even, and enough room must be
! reserved. The missing values may be obtained by complex conjugation.
! The transform of a real array (IFORM = 0) dimensioned N(1) by N(2)
! by ... will be returned in the same array, now considered to
! be complex of dimensions N(1)/2+1 by N(2) by .... Note that if
! IFORM = 0 or -1, N(1) must be even, and enough room must be
! reserved. The missing values may be obtained by complex conjugation.
! The reverse transformation of a half complex array dimensioned
! N(1)/2+1 by N(2) by ..., is accomplished by setting IFORM
! to -1. In the N array, N(1) must be the true N(1), not N(1)/2+1.
! The transform will be real and returned to the input array.
! The reverse transformation of a half complex array dimensioned
! N(1)/2+1 by N(2) by ..., is accomplished by setting IFORM
! to -1. In the N array, N(1) must be the true N(1), not N(1)/2+1.
! The transform will be real and returned to the input array.
parameter (NPMAX=100)
parameter (NSMALL=16384)
complex a(nfft)
complex aa(NSMALL)
integer nn(NPMAX),ns(NPMAX),nf(NPMAX)
integer*8 plan(NPMAX),nl(NPMAX),nloc
data nplan/0/
common/patience/npatience
include 'fftw3.f90'
! This version of four2a makes calls to the FFTW library to do the
! actual computations.
parameter (NPMAX=100) !Max numberf of stored plans
parameter (NSMALL=16384) !Max size of "small" FFTs
complex a(nfft) !Array to be transformed
complex aa(NSMALL) !Local copy of "small" a()
integer nn(NPMAX),ns(NPMAX),nf(NPMAX) !Params of stored plans
integer*8 nl(NPMAX),nloc !More params of plans
integer*8 plan(NPMAX) !Pointers to stored plans
data nplan/0/ !Number of stored plans
common/patience/npatience !Patience for forming FFTW plans
include 'fftw3.f90' !FFTW definitions
save plan,nplan,nn,ns,nf,nl
if(nfft.lt.0) go to 999
@ -53,10 +57,9 @@ subroutine four2a(a,nfft,ndim,isign,iform)
if(nfft.le.NSMALL) then
jz=nfft
if(iform.eq.0) jz=nfft/2
do j=1,jz
aa(j)=a(j)
enddo
aa(1:jz)=a(1:jz)
endif
if(isign.eq.-1 .and. iform.eq.1) then
call sfftw_plan_dft_1d(plan(i),nfft,a,a,FFTW_FORWARD,nflags)
else if(isign.eq.1 .and. iform.eq.1) then
@ -68,13 +71,12 @@ subroutine four2a(a,nfft,ndim,isign,iform)
else
stop 'Unsupported request in four2a'
endif
i=nplan
if(nfft.le.NSMALL) then
jz=nfft
if(iform.eq.0) jz=nfft/2
do j=1,jz
a(j)=aa(j)
enddo
a(1:jz)=aa(1:jz)
endif
10 continue
@ -85,6 +87,7 @@ subroutine four2a(a,nfft,ndim,isign,iform)
! The test is only to silence a compiler warning:
if(ndim.ne.-999) call sfftw_destroy_plan(plan(i))
enddo
nplan=0
return
end subroutine four2a

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lib/g1 Normal file
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gcc -c gran.c
gfortran -c four2a.f90
gfortran -c f77_wisdom.f90
gfortran -o chkfft chkfft.f90 four2a.o f77_wisdom.o gran.o -lfftw3f

4
lib/g1.bat Normal file
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gcc -c gran.c
gfortran -c four2a.f90
gfortran -c f77_wisdom.f90
gfortran -o chkfft chkfft.f90 four2a.o f77_wisdom.o gran.o /JTSDK-QT/appsupport/runtime/libfftw3f-3.dll