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23 lines
575 B
23 lines
575 B
!
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! SPDX-License-Identifier: GPL-3.0-or-later
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! Copyright (C) 2019-2022, respective authors of MCFM.
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!
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function Ftriangle(x)
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implicit none
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include 'types.f'
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complex(dp):: Ftriangle
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include 'constants.f'
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real(dp):: x,y
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complex(dp):: arg
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Ftriangle=czip
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y=1._dp-4._dp*x
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if (y > 0._dp) then
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arg=cmplx((1._dp+sqrt(y))/(1._dp-sqrt(y)),kind=dp)
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Ftriangle=+chalf*(log(arg)-impi)**2
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elseif (y <= 0._dp) then
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Ftriangle=-ctwo*cmplx(asin(half/sqrt(x)),kind=dp)**2
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endif
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return
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end
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