2 C*********************************************************************
4 SUBROUTINE LUTHRU(THR,OBL)
6 C...Purpose: to perform thrust analysis to give thrust, oblateness
7 C...and the related event axes.
8 COMMON/LUJETS/N,K(4000,5),P(4000,5),V(4000,5)
9 COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
10 COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4)
11 SAVE /LUJETS/,/LUDAT1/,/LUDAT2/
12 DIMENSION TDI(3),TPR(3)
14 C...Take copy of particles that are to be considered in thrust analysis.
18 IF(K(I,1).LE.0.OR.K(I,1).GT.10) GOTO 100
19 IF(MSTU(41).GE.2) THEN
21 IF(KC.EQ.0.OR.KC.EQ.12.OR.KC.EQ.14.OR.KC.EQ.16.OR.
23 IF(MSTU(41).GE.3.AND.KCHG(KC,2).EQ.0.AND.LUCHGE(K(I,2)).EQ.0)
26 IF(N+NP+MSTU(44)+15.GE.MSTU(4)-MSTU(32)-5) THEN
27 CALL LUERRM(11,'(LUTHRU:) no more memory left in LUJETS')
37 P(N+NP,4)=SQRT(P(I,1)**2+P(I,2)**2+P(I,3)**2)
39 IF(ABS(PARU(42)-1.).GT.0.001) P(N+NP,5)=P(N+NP,4)**(PARU(42)-1.)
40 PS=PS+P(N+NP,4)*P(N+NP,5)
43 C...Very low multiplicities (0 or 1) not considered.
45 CALL LUERRM(8,'(LUTHRU:) too few particles for analysis')
51 C...Loop over thrust and major. T axis along z direction in latter case.
55 PHI=ULANGL(P(N+NP+1,1),P(N+NP+1,2))
57 CALL LUDBRB(N+1,N+NP+1,0.,-PHI,0D0,0D0,0D0)
58 THE=ULANGL(P(N+NP+1,3),P(N+NP+1,1))
59 CALL LUDBRB(N+1,N+NP+1,-THE,0.,0D0,0D0,0D0)
62 C...Find and order particles with highest p (pT for major).
63 DO 110 ILF=N+NP+4,N+NP+MSTU(44)+4
67 IF(ILD.EQ.2) P(I,4)=SQRT(P(I,1)**2+P(I,2)**2)
68 DO 130 ILF=N+NP+MSTU(44)+3,N+NP+4,-1
69 IF(P(I,4).LE.P(ILF,4)) GOTO 140
80 C...Find and order initial axes with highest thrust (major).
81 DO 170 ILG=N+NP+MSTU(44)+5,N+NP+MSTU(44)+15
84 NC=2**(MIN(MSTU(44),NP)-1)
89 DO 200 ILF=1,MIN(MSTU(44),NP)
91 IF(2**ILF*((ILC+2**(ILF-1)-1)/2**ILF).GE.ILC) SGN=-SGN
93 TDI(J)=TDI(J)+SGN*P(N+NP+ILF+3,J)
96 TDS=TDI(1)**2+TDI(2)**2+TDI(3)**2
97 DO 220 ILG=N+NP+MSTU(44)+MIN(ILC,10)+4,N+NP+MSTU(44)+5,-1
98 IF(TDS.LE.P(ILG,4)) GOTO 230
110 C...Iterate direction of axis until stable maximum.
117 IF(THP.LE.1E-10) TDI(J)=P(N+NP+MSTU(44)+4+ILG,J)
118 IF(THP.GT.1E-10) TDI(J)=TPR(J)
122 SGN=SIGN(P(I,5),TDI(1)*P(I,1)+TDI(2)*P(I,2)+TDI(3)*P(I,3))
124 TPR(J)=TPR(J)+SGN*P(I,J)
127 THP=SQRT(TPR(1)**2+TPR(2)**2+TPR(3)**2)/PS
128 IF(THP.GE.THPS+PARU(48)) GOTO 270
130 C...Save good axis. Try new initial axis until a number of tries agree.
131 IF(THP.LT.P(N+NP+ILD,4)-PARU(48).AND.ILG.LT.MIN(10,NC)) GOTO 260
132 IF(THP.GT.P(N+NP+ILD,4)+PARU(48)) THEN
134 SGN=(-1.)**INT(RLU(0)+0.5)
136 P(N+NP+ILD,J)=SGN*TPR(J)/(PS*THP)
142 IF(IAGR.LT.MSTU(45).AND.ILG.LT.MIN(10,NC)) GOTO 260
145 C...Find minor axis and value by orthogonality.
146 SGN=(-1.)**INT(RLU(0)+0.5)
147 P(N+NP+3,1)=-SGN*P(N+NP+2,2)
148 P(N+NP+3,2)=SGN*P(N+NP+2,1)
152 THP=THP+P(I,5)*ABS(P(N+NP+3,1)*P(I,1)+P(N+NP+3,2)*P(I,2))
157 C...Fill axis information. Rotate back to original coordinate system.
165 P(N+ILD,J)=P(N+NP+ILD,J)
169 CALL LUDBRB(N+1,N+3,THE,PHI,0D0,0D0,0D0)
171 C...Calculate thrust and oblateness. Select storing option.
173 OBL=P(N+2,4)-P(N+3,4)
176 IF(MSTU(43).LE.1) MSTU(3)=3
177 IF(MSTU(43).GE.2) N=N+3