!> @file
!> @brief Module for m_constants.
!>
!> @author N/A @date N/A
!>

!------------------------------------------------------------------------------
!>
!> @brief Module for m_constants.
!> 
!> @author N/A  @date N/A
!>

module m_constants
!------------------------------------------------------------------------------
!
! physical constants
!
real grav    !< gravitational acceleration
real sqrtg   !< square root of grav
real gsq     !< square of grav
real nu      !< kinematic viscosity of water
!
real d_water !< density of water
real d_air   !< density of air
!
! mathematical constants
!
real pi     !< circular constant, 3.1415...
real pi2    !< 2*pi
real pih    !< pi/2
real dera   !< conversion from degrees to radians
real rade   !< conversion from radians to degrees
real expmin !< min argument for exp. function to avoid underflow
real expmax !< max argument for exp. function to avoid overflow
real sqrt2  !< square root of 2 ~ 1.41
!
contains
!
  
!------------------------------------------------------------------------------
!>
!> @brief Subroutine init_constants sets constant values.
!>
!> @author N/A  @date N/A
!>

subroutine init_constants
!------------------------------------------------------------------------------
!
pi   = 4.*atan(1.)
pi2  = 2.*pi
pih  = 0.5*pi
dera = pi/180.
rade = 180./pi
!
expmin = -20.
expmax =  20.
!
!  physical constants
!
grav    = 9.81
sqrtg   = sqrt(grav)
gsq     = grav*grav
nu      = 1.e-6
d_air   = 1.2
d_water = 1027
!
end subroutine
!
end module