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30 lines
841 B
30 lines
841 B
function pvfndd(n,x,iep)
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C----Implementation of DD Eq. 4.11
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implicit none
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include 'lib/TensorReduction/Include/types.f'
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include 'lib/TensorReduction/Include/TRonshellcutoff.f'
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complex(dp)::pvfndd
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integer:: j,n,infty
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complex(dp):: xm1,x,cln,cone
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real(dp):: iep
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parameter(cone=(1d0,0d0),infty=16) ! number of terms in sum
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xm1=x-cone
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if (abs(x) .lt. 10d0) then
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if (abs(x-cone) .lt. onshellcutoff) then
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pvfndd=0d0
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else
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pvfndd=(cone-x**(n+1))*(cln(xm1,iep)-cln(x,iep))
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endif
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do j=0,n
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pvfndd=pvfndd-x**(n-j)/dfloat(j+1)
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enddo
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else
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pvfndd=cln(cone-cone/x,iep)
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do j=n+1,n+infty
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pvfndd=pvfndd+x**(n-j)/dfloat(j+1)
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enddo
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endif
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return
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end
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