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https://github.com/saitohirga/WSJT-X.git
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804e72d436
Needs thorough testing, especially for drifting signals! git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@2774 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
59 lines
1.5 KiB
Fortran
59 lines
1.5 KiB
Fortran
subroutine afc9(c3,npts,fsample,a,syncpk)
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complex c3(0:npts-1)
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real a(3),deltaa(3)
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a(1)=0. !f0
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a(2)=0. !f1
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a(3)=0. !f2
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deltaa(1)=0.2
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deltaa(2)=0.01
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deltaa(3)=0.01
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nterms=3
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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=1,4 !One iteration is enough?
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do j=1,nterms
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chisq1=fchisq(c3,npts,fsample,a)
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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=fchisq(c3,npts,fsample,a)
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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=fchisq(c3,npts,fsample,a)
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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,deltaa,-chisq2
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!4000 format(i1,i2,6f10.4,f9.3)
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enddo
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chisqr=fchisq(c3,npts,fsample,a)
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if(chisqr/chisqr0.gt.0.9999) exit
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chisqr0=chisqr
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enddo
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syncpk=-chisqr
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! write(*,4001) a,deltaa,-chisq2
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!4001 format(3x,6f10.4,f9.3)
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return
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end subroutine afc9
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