scale_specfunc Module Reference

module SPECFUNC More...

Functions/Subroutines
real(rp) function, public	sf_gamma (x)
	Gamma function. More...

Detailed Description

module SPECFUNC

Description

Special functions

Author

Team SCALE

History

• 2013-02-06 (S.Nishizawa) [new] SF_gamma

Function/Subroutine Documentation

sf_gamma()

real(rp) function, public scale_specfunc::sf_gamma

(

real(rp), intent(in)

x

)

Gamma function.

Parameters

[in]

x

input

Definition at line 48 of file scale_specfunc.F90.

References dc_log::log().

Referenced by scale_atmos_phy_mp_convert::atmos_phy_mp_bulk2bin(), scale_atmos_phy_mp_sn14::atmos_phy_mp_sn14(), scale_atmos_phy_mp_tomita08::atmos_phy_mp_tomita08_setup(), and scale_atmos_phy_mp_sn14::ice_multiplication_kij().

    implicit none

    real(RP), intent(in) :: x
    real(RP)             :: sf_gamma

    real(DP), parameter :: lrtp = 0.9189385332046727_dp ! log(sqrt(2*PI))
    real(DP)            :: ag, dx, work
    !---------------------------------------------------------------------------

    dx = real(x, kind=dp)

    ag = 0.999999999999809932276847004735_dp                     &
       + 676.520368121885098567009190444_dp    / ( dx + 1.0_dp ) &
       - 1259.13921672240287047156078755_dp    / ( dx + 2.0_dp ) &
       + 771.323428777653078848652825889_dp    / ( dx + 3.0_dp ) &
       - 176.615029162140599065845513540_dp    / ( dx + 4.0_dp ) &
       + 12.5073432786869048144589368533_dp    / ( dx + 5.0_dp ) &
       - 0.138571095265720116895547069851_dp   / ( dx + 6.0_dp ) &
       + 9.98436957801957085956266899569e-6_dp / ( dx + 7.0_dp ) &
       + 1.50563273514931155833835577539e-7_dp / ( dx + 8.0_dp )

    work = exp( lrtp + (dx+0.5_dp)*log(dx+7.5_dp) - (dx+7.5_dp) + log(ag) )
    sf_gamma = real(work, kind=rp)

    return

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