HIJING/hipyset1_35/pyw2au_hijing.F

   1 * $Id$
   2
   3 C***********************************************************************
   4
   5       FUNCTION PYW2AU_HIJING(EPS,IREIM)
   6
   7 C...Calculates real and imaginary parts of the auxiliary function W2;
   8 C...see R. K. Ellis, I. Hinchliffe, M. Soldate and J. J. van der Bij,
   9 C...FERMILAB-Pub-87/100-T, LBL-23504, June, 1987
  10 #include "ludat1_hijing.inc"
  11
  12       ASINH(X)=LOG(X+SQRT(X**2+1.))
  13       ACOSH(X)=LOG(X+SQRT(X**2-1.))
  14
  15       IF(EPS.LT.0.) THEN
  16         W2RE=4.*(ASINH(SQRT(-1./EPS)))**2
  17         W2IM=0.
  18       ELSEIF(EPS.LT.1.) THEN
  19         W2RE=4.*(ACOSH(SQRT(1./EPS)))**2-PARU(1)**2
  20         W2IM=-4.*PARU(1)*ACOSH(SQRT(1./EPS))
  21       ELSE
  22         W2RE=-4.*(ASIN(SQRT(1./EPS)))**2
  23         W2IM=0.
  24       ENDIF
  25
  26       IF(IREIM.EQ.1) PYW2AU_HIJING=W2RE
  27       IF(IREIM.EQ.2) PYW2AU_HIJING=W2IM
  28
  29       RETURN
  30       END