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https://github.com/saitohirga/WSJT-X.git
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6d70acef57
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8599 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
62 lines
1.6 KiB
Fortran
62 lines
1.6 KiB
Fortran
subroutine afc65b(cx,npts,fsample,nflip,mode65,a,ccfbest,dtbest)
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! Find delta f, f1, f2 ==> a(1:3)
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complex cx(npts)
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real a(5),deltaa(5)
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a(1)=0.
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a(2)=0.
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a(3)=0.
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a(4)=0.
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deltaa(1)=2.0*mode65
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deltaa(2)=2.0*mode65
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deltaa(3)=1.0
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nterms=2 !Maybe 2 is enough?
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! Start the iteration
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chisqr=0.
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chisqr0=1.e6
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do iter=1,100 !How many iters is enough?
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do j=1,nterms
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chisq1=fchisq65(cx,npts,fsample,nflip,a,ccfmax,dtmax)
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fn=0.
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delta=deltaa(j)
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10 a(j)=a(j)+delta
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chisq2=fchisq65(cx,npts,fsample,nflip,a,ccfmax,dtmax)
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if(chisq2.eq.chisq1) go to 10
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if(chisq2.gt.chisq1) then
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delta=-delta !Reverse direction
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a(j)=a(j)+delta
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tmp=chisq1
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chisq1=chisq2
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chisq2=tmp
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endif
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20 fn=fn+1.0
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a(j)=a(j)+delta
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chisq3=fchisq65(cx,npts,fsample,nflip,a,ccfmax,dtmax)
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if(chisq3.lt.chisq2) then
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chisq1=chisq2
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chisq2=chisq3
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go to 20
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endif
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! Find minimum of parabola defined by last three points
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delta=delta*(1./(1.+(chisq1-chisq2)/(chisq3-chisq2))+0.5)
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a(j)=a(j)-delta
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deltaa(j)=deltaa(j)*fn/3.
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! write(*,4000) iter,j,a(1:2),-chisq2
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!4000 format(2i2,4f9.4)
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enddo
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chisqr=fchisq65(cx,npts,fsample,nflip,a,ccfmax,dtmax)
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fdiff=chisqr/chisqr0-1.0
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! write(*,4000) 0,0,a(1:2),-chisqr,fdiff
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if(abs(fdiff).lt.0.0001) exit
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chisqr0=chisqr
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enddo
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ccfbest=ccfmax * (1378.125/fsample)**2
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dtbest=dtmax
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return
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end subroutine afc65b
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