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lurobo.f
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1 
2 C*********************************************************************
3 
4  SUBROUTINE lurobo(THE,PHI,BEX,BEY,BEZ)
5 
6 C...Purpose: to perform rotations and boosts.
7  IMPLICIT DOUBLE PRECISION(d)
8  common/lujets/n,k(9000,5),p(9000,5),v(9000,5)
9  SAVE /lujets/
10  common/ludat1/mstu(200),paru(200),mstj(200),parj(200)
11  SAVE /ludat1/
12  dimension rot(3,3),pr(3),vr(3),dp(4),dv(4)
13 
14 C...Find range of rotation/boost. Convert boost to double precision.
15  imin=1
16  IF(mstu(1).GT.0) imin=mstu(1)
17  imax=n
18  IF(mstu(2).GT.0) imax=mstu(2)
19  dbx=bex
20  dby=bey
21  dbz=bez
22  goto 100
23 
24 C...Entry for specific range and double precision boost.
25  entry ludbrb(imi,ima,the,phi,dbex,dbey,dbez)
26  imin=imi
27  IF(imin.LE.0) imin=1
28  imax=ima
29  IF(imax.LE.0) imax=n
30  dbx=dbex
31  dby=dbey
32  dbz=dbez
33 
34 C...Check range of rotation/boost.
35  100 IF(imin.GT.mstu(4).OR.imax.GT.mstu(4)) THEN
36  CALL luerrm(11,'(LUROBO:) range outside LUJETS memory')
37  RETURN
38  ENDIF
39 
40 C...Rotate, typically from z axis to direction (theta,phi).
41  IF(the**2+phi**2.GT.1e-20) THEN
42  rot(1,1)=cos(the)*cos(phi)
43  rot(1,2)=-sin(phi)
44  rot(1,3)=sin(the)*cos(phi)
45  rot(2,1)=cos(the)*sin(phi)
46  rot(2,2)=cos(phi)
47  rot(2,3)=sin(the)*sin(phi)
48  rot(3,1)=-sin(the)
49  rot(3,2)=0.
50  rot(3,3)=cos(the)
51  DO 130 i=imin,imax
52  IF(k(i,1).LE.0) goto 130
53  DO 110 j=1,3
54  pr(j)=p(i,j)
55  110 vr(j)=v(i,j)
56  DO 120 j=1,3
57  p(i,j)=rot(j,1)*pr(1)+rot(j,2)*pr(2)+rot(j,3)*pr(3)
58  120 v(i,j)=rot(j,1)*vr(1)+rot(j,2)*vr(2)+rot(j,3)*vr(3)
59  130 CONTINUE
60  ENDIF
61 
62 C...Boost, typically from rest to momentum/energy=beta.
63  IF(dbx**2+dby**2+dbz**2.GT.1e-20) THEN
64  db=sqrt(dbx**2+dby**2+dbz**2)
65  IF(db.GT.0.99999999d0) THEN
66 C...Rescale boost vector if too close to unity.
67  CALL luerrm(3,'(LUROBO:) boost vector too large')
68  dbx=dbx*(0.99999999d0/db)
69  dby=dby*(0.99999999d0/db)
70  dbz=dbz*(0.99999999d0/db)
71  db=0.99999999d0
72  ENDIF
73  dga=1d0/sqrt(1d0-db**2)
74  DO 150 i=imin,imax
75  IF(k(i,1).LE.0) goto 150
76  DO 140 j=1,4
77  dp(j)=p(i,j)
78  140 dv(j)=v(i,j)
79  dbp=dbx*dp(1)+dby*dp(2)+dbz*dp(3)
80  dgabp=dga*(dga*dbp/(1d0+dga)+dp(4))
81  p(i,1)=dp(1)+dgabp*dbx
82  p(i,2)=dp(2)+dgabp*dby
83  p(i,3)=dp(3)+dgabp*dbz
84  p(i,4)=dga*(dp(4)+dbp)
85  dbv=dbx*dv(1)+dby*dv(2)+dbz*dv(3)
86  dgabv=dga*(dga*dbv/(1d0+dga)+dv(4))
87  v(i,1)=dv(1)+dgabv*dbx
88  v(i,2)=dv(2)+dgabv*dby
89  v(i,3)=dv(3)+dgabv*dbz
90  v(i,4)=dga*(dv(4)+dbv)
91  150 CONTINUE
92  ENDIF
93 
94  RETURN
95  END