ISAJET/code/logx.F

   1 #include "isajet/pilot.h"
   2       LOGICAL FUNCTION LOGX(IERR)
   3 C
   4 C         SET AND CHECK LIMITS FOR JET FEYNMAN X
   5 C
   6 #include "isajet/itapes.inc"
   7 #include "isajet/jetlim.inc"
   8 #include "isajet/primar.inc"
   9 #include "isajet/jetpar.inc"
  10 #include "isajet/const.inc"
  11 #include "isajet/dylim.inc"
  12 #include "isajet/keys.inc"
  13 #include "isajet/q1q2.inc"
  14       DATA UNDEF/-.9E9/
  15 C
  16       HALFPI=PI/2.
  17       LOGX=.TRUE.
  18 C
  19       DO 40 I=1,NJET
  20       FIXXJ(I)=.FALSE.
  21       IF(FIXYJ(I).AND.(FIXP(I).OR.FIXPT(I)))FIXXJ(I)=.TRUE.
  22       IF(FIXXJ(I)) GOTO 40
  23 C
  24       IF(XJMIN(I).LT.UNDEF.AND.XJMAX(I).LT.UNDEF) THEN
  25         XJMAX(I)=1.0
  26         XJMIN(I)=-1.0
  27       ENDIF
  28 C
  29       IF(XJMAX(I).LT.UNDEF) FIXXJ(I)=.TRUE.
  30       IF(FIXXJ(I)) XJMAX(I)=XJMIN(I)
  31 C
  32       IF(.NOT.FIXXJ(I)) THEN
  33         IF(THMIN(I).LT.HALFPI) X1=PMAX(I)*COS(THMIN(I))/HALFE
  34         IF(THMIN(I).GE.HALFPI) X1=PMIN(I)*COS(THMIN(I))/HALFE
  35         IF(THMAX(I).GT.HALFPI) X2=PMAX(I)*COS(THMAX(I))/HALFE
  36         IF(THMAX(I).LT.HALFPI) X2=PMIN(I)*COS(THMAX(I))/HALFE
  37         IF(X1.LT.XJMAX(I)) XJMAX(I)=X1
  38         IF(X2.GT.XJMIN(I)) XJMIN(I)=X2
  39       ELSE
  40 C
  41         XJ(I)=XJMIN(I)
  42 C
  43         IF(FIXP(I)) THEN
  44           CTH(I)=XJ(I)*HALFE/P(I)
  45           IF(ABS(CTH(I)).LE.1.0) THEN
  46             STH(I)=SQRT(1.-CTH(I)**2)
  47             TH(I)=ATAN2(STH(I),CTH(I))
  48             YJ(I)=-ALOG(TAN(TH(I)/2.))
  49             FIXYJ(I)=.TRUE.
  50             PT(I)=P(I)*STH(I)
  51             FIXPT(I)=.TRUE.
  52             YJMIN(I)=YJ(I)
  53             YJMAX(I)=YJ(I)
  54             PTMIN(I)=PT(I)
  55             PTMAX(I)=PT(I)
  56           ELSE
  57             LOGX=.FALSE.
  58             CALL LOGERR(5,I,IERR)
  59           ENDIF
  60         ENDIF
  61 C
  62         IF(FIXPT(I)) THEN
  63           TH(I)=ATAN(PT(I)/XJ(I)/HALFE)
  64           FIXYJ(I)=.TRUE.
  65           YJ(I)=-ALOG(TAN(TH(I)/2.))
  66           CTH(I)=COS(TH(I))
  67           STH(I)=SIN(TH(I))
  68           P(I)=PT(I)/STH(I)
  69           FIXP(I)=.TRUE.
  70           YJMIN(I)=YJ(I)
  71           YJMAX(I)=YJ(I)
  72           PMAX(I)=P(I)
  73           PMIN(I)=P(I)
  74         ENDIF
  75 C
  76         IF(FIXYJ(I)) THEN
  77           FIXPT(I)=.TRUE.
  78           P(I)=XJ(I)*HALFE/CTH(I)
  79           PT(I)=P(I)*STH(I)
  80           FIXP(I)=.TRUE.
  81           PTMIN(I)=PT(I)
  82           PTMAX(I)=PT(I)
  83           PMAX(I)=P(I)
  84           PMIN(I)=P(I)
  85         ENDIF
  86 C
  87       ENDIF
  88 C
  89    40 CONTINUE
  90 C
  91       RETURN
  92       END