WSJT-X/lib/afc9.f90
Joe Taylor 6abec2102c Zero out the wrapped-around end points after cshift from c3a to c3.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@5007 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2015-03-05 17:13:00 +00:00

80 lines
1.9 KiB
Fortran

subroutine afc9(c3a,npts,fsample,a,syncpk)
complex c3a(0:npts-1)
complex c3(0:1360-1)
real a(3),deltaa(3)
a(1)=0. !f0
a(2)=0. !f1
a(3)=0. !f2
deltaa(1)=1.736
deltaa(2)=1.736
deltaa(3)=1.0
nterms=3
! Start the iteration
chisqr=0.
chisqr0=1.e6
c3=c3a
a3=a(3)
do iter=1,4
do j=1,nterms
if(a(3).ne.a3) call shft(c3a,a(3),a3,c3)
chisq1=fchisq(c3,npts,fsample,a)
fn=0.
delta=deltaa(j)
10 a(j)=a(j)+delta
if(a(3).ne.a3) call shft(c3a,a(3),a3,c3)
chisq2=fchisq(c3,npts,fsample,a)
if(chisq2.eq.chisq1) go to 10
if(chisq2.gt.chisq1) then
delta=-delta !Reverse direction
a(j)=a(j)+delta
tmp=chisq1
chisq1=chisq2
chisq2=tmp
endif
20 fn=fn+1.0
a(j)=a(j)+delta
if(a(3).ne.a3) call shft(c3a,a(3),a3,c3)
chisq3=fchisq(c3,npts,fsample,a)
if(chisq3.lt.chisq2) then
chisq1=chisq2
chisq2=chisq3
go to 20
endif
! Find minimum of parabola defined by last three points
delta=delta*(1./(1.+(chisq1-chisq2)/(chisq3-chisq2))+0.5)
a(j)=a(j)-delta
if(j.lt.3) deltaa(j)=deltaa(j)*fn/3.
! write(*,4000) iter,j,a,-chisq2
!4000 format(i1,i2,3f10.4,f11.3)
enddo
if(a(3).ne.a3) call shft(c3a,a(3),a3,c3)
chisqr=fchisq(c3,npts,fsample,a)
if(chisqr/chisqr0.gt.0.99) exit
chisqr0=chisqr
enddo
syncpk=-chisqr
c3a=c3
! write(*,4001) a,-chisq2
!4001 format(3x,3f10.4,f11.3)
return
end subroutine afc9
subroutine shft(c3a,a3a,a3,c3)
complex c3a(0:1359)
complex c3(0:1359)
a3=a3a
n=nint(a3)
c3=cshift(c3a,n)
if(n.gt.0) c3(1360-n:)=0.0
if(n.lt.0) c3(:n-1)=0.0
return
end subroutine shft