constructor Function

  pure function constructor(thickness, frequency, amplitude, mean, chi, &
                            square) result(this)
    !* Author: Chris MacMackin
    !  Date: October 2017
    !
    ! Constructs a boundary condition object for an ice shelf based on
    ! the conditions used in Dallaston et al. (2015), but with the ice
    ! flux at the grounding line varying in time.
    !
    real(r8), intent(in), optional :: thickness
      !! The ice thickness at the inflowing ice shelf boundary,
      !! defaults to 1.0
    real(r8), intent(in), optional :: frequency
      !! The angular frequency of the oscillations in ice flux,
      !! defaults to 0.5
    real(r8), intent(in), optional :: amplitude
      !! The amplitude of the oscillations in ice flux, defaults to
      !! 1.0
    real(r8), intent(in), optional :: mean
      !! The time-average of the discharge, about which it oscillates,
      !! defaulting to 1.0
    real(r8), intent(in), optional :: chi
      !! The dimensionless ratio \(\chi \equiv
      !! \frac{\rho_igh_0x_x}{2\eta_0u_0}\), defaults to 1.0
    logical, intent(in), optional  :: square
      !! If present and true, produce a square wave. Otherwise produce
      !! a sinusoid.
    type(seasonal_glacier_boundary) :: this
    if (present(thickness)) this%thickness = thickness
    if (present(frequency)) this%frequency = frequency
    if (present(amplitude)) this%amplitude = amplitude
    if (present(mean)) this%mean = mean
    if (present(chi)) this%chi = chi
    if (present(square)) this%square = square
  end function constructor