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https://github.com/pfloos/quack
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48 lines
1.1 KiB
Fortran
48 lines
1.1 KiB
Fortran
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!module c_functions
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! use iso_c_binding
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! interface
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! function gsl_sf_gamma_inc_P(a,t) bind(C, name="gsl_sf_gamma_inc_P")
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! use iso_c_binding, only: c_double
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! real(kind=c_double), value :: a,t
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! real(kind=c_double) :: gsl_sf_gamma_inc_P
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! end function gsl_sf_gamma_inc_P
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! end interface
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!end module
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subroutine CalcBoysF(maxm,t,Fm)
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! use c_functions
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! Comute the generalized Boys function Fm(t) using Slatec library
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implicit none
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! Input variables
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double precision,intent(in) :: t
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integer,intent(in) :: maxm
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! Local variables
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integer :: m
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double precision :: dm
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double precision :: dgami
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! Output variables
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double precision,intent(inout):: Fm(0:maxm)
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if(t == 0d0) then
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do m=0,maxm
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dm = dble(m)
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Fm(m) = 1d0/(2d0*dm+1d0)
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enddo
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else
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do m=0,maxm
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dm = dble(m)
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! Fm(m) = gamma(dm+0.5d0)*gsl_sf_gamma_inc_P(dm+0.5d0,t)/(2d0*t**(dm+0.5d0))
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Fm(m) = dgami(dm+0.5d0,t)/(2d0*t**(dm+0.5d0))
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enddo
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endif
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end subroutine CalcBoysF
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