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vendor/CutTools/src/qcdloop/qlLi2omx2.f
 
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      double complex function qlLi2omx2(v,w,x,y)
 
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      implicit none
 
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      include 'qlconstants.f'
 
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c     expression for dilog(1-(v-i*ep)*(w-i*ep)/(x-i*ep)/(y-i*ep)) 
 
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C     for real v,w,x and y
 
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      double precision v,w,x,y,omarg,arg,ddilog
 
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      double complex qllnrat,lnarg,lnomarg,prod
 
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      arg=(v*w)/(x*y)
 
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      omarg=1d0-arg
 
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      if (arg .le. 1d0) then
 
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         if (arg .eq. 0d0 .or. arg .eq. 1d0) then 
 
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            prod=0d0
 
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         else
 
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            lnarg=qllnrat(v,x)+qllnrat(w,y)
 
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            lnomarg=dcmplx(log(omarg))
 
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            prod=lnarg*lnomarg
 
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         endif
 
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         qlLi2omx2=dcmplx(pisqo6-ddilog(arg))-prod
 
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      elseif (arg .gt. 1d0) then
 
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         arg=(x*y)/(v*w)
 
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         lnarg=-qllnrat(v,x)-qllnrat(w,y)
 
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         lnomarg=dcmplx(log(1d0-arg))
 
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         qlLi2omx2=-dcmplx(pisqo6-ddilog(arg))+lnarg*lnomarg
 
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     .   -0.5d0*lnarg**2
 
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      endif
 
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      return 
 
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      end