3 C***********************************************************************
5 FUNCTION PYSPEN_HIJING(XREIN,XIMIN,IREIM)
7 C...Calculates real and imaginary part of Spence function; see
8 C...G. 't Hooft and M. Veltman, Nucl. Phys. B153 (1979) 365.
9 #include "ludat1_hijing.inc"
13 & 1.000000E+00, -5.000000E-01, 1.666667E-01,
14 & 0.000000E+00, -3.333333E-02, 0.000000E+00,
15 & 2.380952E-02, 0.000000E+00, -3.333333E-02,
16 & 0.000000E+00, 7.575757E-02, 0.000000E+00,
17 &-2.531135E-01, 0.000000E+00, 1.166667E+00/
21 IF(ABS(1.-XRE).LT.1.E-6.AND.ABS(XIM).LT.1.E-6) THEN
22 IF(IREIM.EQ.1) PYSPEN_HIJING=PARU(1)**2/6.
23 IF(IREIM.EQ.2) PYSPEN_HIJING=0.
27 XMOD=SQRT(XRE**2+XIM**2)
28 IF(XMOD.LT.1.E-6) THEN
29 IF(IREIM.EQ.1) PYSPEN_HIJING=0.
30 IF(IREIM.EQ.2) PYSPEN_HIJING=0.
34 XARG=SIGN(ACOS(XRE/XMOD),XIM)
40 ALGXIM=XARG-SIGN(PARU(1),XARG)
41 SP0RE=-PARU(1)**2/6.-(ALGXRE**2-ALGXIM**2)/2.
54 XMOD=SQRT(XRE**2+XIM**2)
55 XARG=SIGN(ACOS(XRE/XMOD),XIM)
58 SP0RE=SP0RE+SGN*(PARU(1)**2/6.-(ALGXRE*ALGYRE-ALGXIM*ALGYIM))
59 SP0IM=SP0IM-SGN*(ALGXRE*ALGYIM+ALGXIM*ALGYRE)
65 XMOD=SQRT(XRE**2+XIM**2)
66 XARG=SIGN(ACOS(XRE/XMOD),XIM)
75 TERMRE=(SAVERE*ZRE-SAVEIM*ZIM)/FLOAT(I+1)
76 TERMIM=(SAVERE*ZIM+SAVEIM*ZRE)/FLOAT(I+1)
80 100 SPIM=SPIM+B(I)*TERMIM
82 IF(IREIM.EQ.1) PYSPEN_HIJING=SP0RE+SGN*SPRE
83 IF(IREIM.EQ.2) PYSPEN_HIJING=SP0IM+SGN*SPIM