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vendor/CutTools/src/qcdloop/qllnrat.f
 
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      double complex function qlLnrat(x,y)
 
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************************************************************************
 
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*     Author: R.K. Ellis                                               *
 
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*     August, 1998.                                                    *
 
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c     Lnrat(x,y)=log(x-i*ep)-log(y-i*ep)                               *
 
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c     this function is hard-wired for sign of epsilon we must adjust   *
 
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c     sign of x and y to get the right sign for epsilon                *
 
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************************************************************************
 
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      implicit none
 
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      include 'qlconstants.f'
 
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      double precision x,y,htheta
 
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C--- define Heaviside theta function (=1 for x>0) and (0 for x < 0)
 
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      htheta(x)=half+half*sign(one,x)
 
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      qlLnrat=dcmplx(dlog(abs(x/y)))
 
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     . -impi*dcmplx((htheta(-x)-htheta(-y)))
 
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      return
 
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      end
 
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