!******************************************************************************
!  2003-10-01
!    const_set subroutine is added. 
!------------------------------------------------------------------------------
!  2003-09-07
!******************************************************************************

module lbl_const_module

  use vtype_module

  implicit none

  private

  ! pi
  ! pix2     : 2 * pi
  !
  ! pi2      : same as pix2 (this is remained for the purpose of compativility)
  !
  ! d2r      : pi / 180
  ! r2d      : 180 / pi
  ! c        : speed of light (m/s)
  ! amu      : atomic mass unit
  ! planc    : planck constant
  ! boltz    : boltzmann constant
  ! ugasc    : universal gas constant
  ! gconst   : gravitational constant
  !
  real(dp), parameter :: &
    & pi     = 3.1415926535897932385d0, &
    & pix2   = 2.0d0 * pi             , &
    & pi2    = pix2                   , &
    & d2r    = pi / 180.0d0           , &
    & r2d    = 180.0d0 / pi           , &
    & c      = 2.99792458d8           , &
    & amu    = 1.6605655d-27          , &
    & planc  = 6.6260755d-34          , &
    & boltz  = 1.380658d-23           , &
    & ugasc  = 8.314510d0             , &
    & gconst = 6.67260d-11


  !
  ! sboltz   : Stefan-Boltzmann constant
  !
  real(dp), parameter :: sboltz &
    & = 2.0d0*pi*pi*pi*pi*pi*boltz*boltz*boltz*boltz &
    &   /(15.0d0*c*c*planc*planc*planc)

  !
  ! dayearth  : 1 day of the Earth (sec)
  !
  real(dp), parameter :: dayearth = 60.0d0 * 60.0d0 * 24.0d0


  !**************************************************************************

  ! co2lh     : Latent heat of CO2 (J kg^{-1})
  !           : This value is obtained from Pollack et al. [1981] and 
  !           : Forget et al. [1998]. 
  !
!!$    real(dp), parameter :: co2lh = 5.9d5

  !**************************************************************************


  logical, save :: sw_const_set

  data sw_const_set / .false. /


  !
  ! pradi    : planetary radius (m)
  ! pradisq  : planetary radius squared (m^2)
  !
  ! pradi2   : same as pradisq (this is remained for the purpose of 
  !          : compativility)
  !
  ! grav     : gravitational acceleration (m/s^2)
  !
!!$    real(dp), save :: pradi
!!$    real(dp), save :: pradisq
!!$    real(dp), save :: pradi2
!!$    real(dp), save :: grav


  ! hour     : one solar hour (sec)
  ! day      : one solar day (sec)
  ! omega    : planetary angular velocity (rad/sec)
  !
!!$    real(dp), save :: hour
!!$    real(dp), save :: day
!!$    real(dp), save :: omega

  ! cp       : specific heat at constant pressure
  !
!!$    real(dp), save :: cp


!!$    data pradi     / 1.0d100 /
!!$    data pradisq   / 1.0d100 /
!!$    data pradi2    / 1.0d100 /
!!$    data grav      / 1.0d100 /
!!$    data hour      / 1.0d100 /
!!$    data day       / 1.0d100 /
!!$    data omega     / 1.0d100 /
!!$
!!$    data cp        / 1.0d100 /


  !**************************************************************************

  public :: pi, pix2, pi2, d2r, r2d, c, amu, planc, boltz, ugasc, sboltz
!!$    public :: pradi, pradisq, pradi2, grav, hour, day, omega
!!$    public :: co2lh

!    public :: cp

  public :: const_set, const_set_check

  !**************************************************************************

contains

  !**************************************************************************

  function const_set_check() result( sw )

    logical :: sw

    sw = sw_const_set

  end function const_set_check

  !**************************************************************************
  ! planetid  : Planet ID
  !           : 0  : the Earth
  !           : 1  : Mars
  !**************************************************************************

  subroutine const_set( planetid, planetname )

    character(len=*), intent(in), optional :: planetname
    integer(i4b)    , intent(in), optional :: planetid


    ! Local variables
    !
    integer(i4b) :: pid


    if( present( planetname ) ) then

      if( ( planetname .eq. 'Earth' ) &
        .or. ( planetname .eq. 'EARTH' ) ) then
        pid = 0
      else if( ( planetname .eq. 'Mars' ) &
        .or. ( planetname .eq. 'MARS' ) ) then
        pid = 1
      else
        write( 6, * ) 'Unexpected planet name : ', trim( planetname ), '.'
        stop
      end if

    else

      if( present( planetid ) ) then
        pid = planetid
      else
        pid = 0
      end if

    end if


    select case( pid )
    case( 0 )

         !
         ! for the Earth
         !
!!$         pradi = 6371.0d3
!!$         grav  = 9.81d0
!!$!         omega = pix2 / dayearth
!!$         omega = 7.292d-5
!!$         day   = 1.0d0 * dayearth
!!$         hour  = day / 24.0d0

    case( 1 )

         !
         ! for Mars
         !
!!$         pradi = 3382.946d3
!!$         omega = pix2 / ( 22.663d0 + 60.0d0 * ( 37.0d0 + 60.0d0 * 24.0d0 ) )
!!$         day   = 1.0274912d0 * dayearth
!!$         hour  = day / 24.0d0
!!$         grav  = 3.72d0

    case default

      write( 6, * ) "Unexpected planet ID, ", pid

    end select

!!$      pradisq = pradi * pradi
!!$      pradi2  = pradisq

!      omega=0.0d0


    sw_const_set = .true. 


  end subroutine const_set

  !**************************************************************************

end module lbl_const_module