1 C--------------------------------------------------------------------------
4 C This software is part of the EvtGen package developed jointly
5 C for the BaBar and CLEO collaborations. If you use all or part
6 C of it, please give an appropriate acknowledgement.
8 C Copyright Information: See EvtGen/COPYRIGHT
9 C Copyright (C) 1998 Caltech, UCSB
11 C Module: EvtLi2Spence.F
15 C Modification history:
17 C DJL/RYD August 11, 1998 Module created
19 C------------------------------------------------------------------------
20 C -----------------------------------------------------------------
21 DOUBLE PRECISION FUNCTION LI2SPENCE(X)
22 C *************************************************************
23 C REAL SPENCE FUNCTION OBTAINED FROM J. VAN DER BIJ
24 C *************************************************************
28 REAL*8 A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,ZETA2
29 DATA A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,ZETA2/
30 1 -0.250000000000000D0,
31 2 -0.111111111111111D0,
32 3 -0.010000000000000D0,
33 4 -0.017006802721088D0,
34 5 -0.019444444444444D0,
35 6 -0.020661157024793D0,
36 7 -0.021417300648069D0,
37 8 -0.021948866377231D0,
38 9 -0.022349233811171D0,
39 1 -0.022663689135191D0,
40 2 1.644934066848226D0/
46 IF(R2.GT.1.D0.AND.(XR/R2).GT.0.5D0)THEN
50 SP=Z*(1.D0+A1*Z*(1.D0+A2*Z*(1.D0+A3*Z2*(1.D0+A4*Z2*
51 1 (1.D0+A5*Z2*(1.D0+A6*Z2*(1.D0+A7*Z2*(1.D0+A8*Z2*(1.D0+A9*Z2*
52 2 (1.D0+A10*Z2))))))))))
53 3 +ZETA2-LOG(X)*LOG(1.D0-X)+0.5D0*LOG(X)**2
56 ELSEIF(R2.GT.1.D0.AND.(XR/R2).LE.0.5D0)THEN
60 SP=-Z*(1.D0+A1*Z*(1.D0+A2*Z*(1.D0+A3*Z2*(1.D0+A4*Z2*
61 1 (1.D0+A5*Z2*(1.D0+A6*Z2*(1.D0+A7*Z2*(1.D0+A8*Z2*(1.D0+A9*Z2*
62 2 (1.D0+A10*Z2))))))))))
63 3 -ZETA2-0.5D0*LOG(-X)**2
66 ELSEIF(R2.EQ.1.D0.AND.XI.EQ.0.D0)THEN
70 ELSEIF(R2.LE.1.D0.AND.XR.GT.0.5D0)THEN
74 SP=-Z*(1.D0+A1*Z*(1.D0+A2*Z*(1.D0+A3*Z2*(1.D0+A4*Z2*
75 1 (1.D0+A5*Z2*(1.D0+A6*Z2*(1.D0+A7*Z2*(1.D0+A8*Z2*(1.D0+A9*Z2*
76 2 (1.D0+A10*Z2))))))))))
77 3 +ZETA2-LOG(X)*LOG(1.D0-X)
80 ELSEIF(R2.LE.1.D0.AND.XR.LE.0.5D0)THEN
84 SP=Z*(1.D0+A1*Z*(1.D0+A2*Z*(1.D0+A3*Z2*(1.D0+A4*Z2*
85 1 (1.D0+A5*Z2*(1.D0+A6*Z2*(1.D0+A7*Z2*(1.D0+A8*Z2*(1.D0+A9*Z2*
86 2 (1.D0+A10*Z2))))))))))
91 C ----------------------------------------------------------------------