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vendor/IREGI/src/qcdloop/ql/qlcLi2omx3.f

 

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      double complex function qlcLi2omx3(z1,z2,z3,ieps1,ieps2,ieps3)

 

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C     Calculate Li[2](1-(z1+ieps1)*(z2+ieps2)*(z3+ieps3)) 

 

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C     Using +cLi2(1-z1*z2*z3)                           

 

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C --- for |z1*z2*z3|<1

 

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C     and   -cLi2(1-1/(z1*z2*z3))-1/2*(ln(z1)+ln(z2)+ln(z3))^2 

 

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C---- for |z1*z2*z3|>1

 

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      implicit none

 

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      include 'qlconstants.f'

 

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      double precision ieps1,ieps2,ieps3,ieps

 

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      double complex arg,lnarg,lnomarg,prod,denspence,z1,z2,z3,cln

 

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      logical qlzero

 

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      arg=z1*z2*z3

 

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      if (qlzero(dimag(arg))) ieps=

 

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     .sign(one,dreal(z2*z3)*ieps1+dreal(z1*z3)*ieps2+dreal(z1*z2)*ieps3)

 

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      if (abs(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=cln(z1,ieps1)+cln(z2,ieps2)+cln(z3,ieps3)

 

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            lnomarg=cln(cone-arg,0d0)

 

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            prod = lnarg*lnomarg

 

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         endif

 

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         qlcLi2omx3=dcmplx(pisqo6)-denspence(dcmplx(arg),ieps)-prod

 

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      elseif (abs(arg) .gt. 1d0) then

 

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         arg=1d0/(z1*z2*z3)

 

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         lnarg=-cln(z1,ieps1)-cln(z2,ieps2)-cln(z3,ieps3)

 

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         lnomarg=cln(cone-arg,0d0)

 

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         qlcLi2omx3=-dcmplx(pisqo6)+denspence(dcmplx(arg),ieps)

 

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     .   +lnarg*lnomarg-0.5d0*lnarg**2

 

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      endif

 

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      return

 

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      end

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