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quantum_package/plugins/loc_cele/loc.f

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2015-07-02 00:45:36 +02:00
c************************************************************************
subroutine maxovl(n,m,s,t,w)
C
C This subprogram contains an iterative procedure to find the
C unitary transformation of a set of n vectors which maximizes
C the sum of their square overlaps with a set of m reference
C vectors (m.le.n)
C
C S: overlap matrix <ref|vec>
C T: rotation matrix
C W: new overlap matrix
C
C
implicit real*8(a-h,o-y),logical*1(z)
parameter (id1=300)
dimension s(id1,id1),t(id1,id1),w(id1,id1)
data small/1.d-6/
zprt=.true.
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niter=500
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conv=1.d-8
write (6,5) n,m,conv
5 format (//5x,'Unitary transformation of',i3,' vectors'/
* 5x,'following the principle of maximum overlap with a set of',
* i3,' reference vectors'/5x,'required convergence on rotation ',
* 'angle =',f13.10///5x,'Starting overlap matrix'/)
do 6 i=1,m
write (6,145) i
6 write (6,150) (s(i,j),j=1,n)
8 mm=m-1
if (m.lt.n) mm=m
iter=0
do 20 j=1,n
do 16 i=1,n
t(i,j)=0.d0
16 continue
do 18 i=1,m
18 w(i,j)=s(i,j)
20 t(j,j)=1.d0
sum=0.d0
do 10 i=1,m
sum=sum+s(i,i)*s(i,i)
10 continue
sum=sum/m
if (zprt) write (6,12) sum
12 format (//5x,'Average square overlap =',f10.6)
if (n.eq.1) goto 100
last=n
j=1
21 if (j.ge.last) goto 30
sum=0.d0
do 22 i=1,n
22 sum=sum+s(i,j)*s(i,j)
if (sum.gt.small) goto 28
do 24 i=1,n
sij=s(i,j)
s(i,j)=-s(i,last)
s(i,last)=sij
tij=t(i,j)
t(i,j)=-t(i,last)
t(i,last)=tij
24 continue
last=last-1
goto 21
28 j=j+1
goto 21
30 iter=iter+1
imax=0
jmax=0
dmax=0.d0
amax=0.d0
do 60 i=1,mm
ip=i+1
do 50 j=ip,n
a=s(i,j)*s(i,j)-s(i,i)*s(i,i)
b=-s(i,i)*s(i,j)
if (j.gt.m) goto 31
a=a+s(j,i)*s(j,i)-s(j,j)*s(j,j)
b=b+s(j,i)*s(j,j)
31 b=b+b
if (a.eq.0.d0) goto 32
ba=b/a
if (dabs(ba).gt.small) goto 32
if (a.gt.0.d0) goto 33
tang=-0.5d0*ba
cosine=1.d0/dsqrt(1.d0+tang*tang)
sine=tang*cosine
goto 34
32 tang=0.d0
if (b.ne.0.d0) tang=(a+dsqrt(a*a+b*b))/b
cosine=1.d0/dsqrt(1.d0+tang*tang)
sine=tang*cosine
goto 34
33 cosine=0.d0
sine=1.d0
34 delta=sine*(a*sine+b*cosine)
if (zprt.and.delta.lt.0.d0) write (6,71) i,j,a,b,sine,cosine,delta
do 35 k=1,m
p=s(k,i)*cosine-s(k,j)*sine
q=s(k,i)*sine+s(k,j)*cosine
s(k,i)=p
35 s(k,j)=q
do 40 k=1,n
p=t(k,i)*cosine-t(k,j)*sine
q=t(k,i)*sine+t(k,j)*cosine
t(k,i)=p
t(k,j)=q
40 continue
45 d=dabs(sine)
if (d.le.amax) goto 50
imax=i
jmax=j
amax=d
dmax=delta
50 continue
60 continue
if (zprt) write (6,70) iter,amax,imax,jmax,dmax
70 format (' iter=',i4,' largest rotation=',f12.8,
* ', vectors',i3,' and',i3,', incr. of diag. squares=',g12.5)
71 format (' i,j,a,b,sin,cos,delta =',2i3,5f10.5)
if (amax.lt.conv) goto 100
if (iter.lt.niter) goto 30
write (6,80)
write (6,*) 'niter=',niter
80 format (//5x,'*** maximum number of cycles exceeded ',
* 'in subroutine maxovl ***'//)
stop
100 continue
do 120 j=1,n
if (s(j,j).gt.0.d0) goto 120
do 105 i=1,m
105 s(i,j)=-s(i,j)
do 110 i=1,n
110 t(i,j)=-t(i,j)
120 continue
sum=0.d0
do 125 i=1,m
125 sum=sum+s(i,i)*s(i,i)
sum=sum/m
do 122 i=1,m
do 122 j=1,n
sw=s(i,j)
s(i,j)=w(i,j)
122 w(i,j)=sw
if (.not.zprt) return
write (6,12) sum
write (6,130)
130 format (//5x,'transformation matrix')
do 140 i=1,n
write (6,145) i
140 write (6,150) (t(i,j),j=1,n)
145 format (i8)
150 format (2x,10f12.8)
write (6,160)
160 format (//5x,'new overlap matrix'/)
do 170 i=1,m
write (6,145) i
170 write (6,150) (w(i,j),j=1,n)
return
end