module m_chemistry

use m_parameters

implicit none

contains

real function rate_1step (yr, theta)

    real, intent(in)  :: yr
    real, intent(in)  :: theta

    real :: y
    real :: t_reduce

    y=yr
    ! if(yr.lt.0.) y=0.
    ! if(yr.gt.1.) y=1.

    t_reduce=theta
    ! if(theta.lt.0.) t_reduce=0.
    ! if(theta.gt.1.) t_reduce=1.

    if (t_reduce.gt.c_ref) then

      rate_1step = pre*y*exp(-ac/(1.+bc*t_reduce))

    else if (t_reduce.le.c_cut) then

      rate_1step = min_wr

    else

      rate_1step = &
        ((refwr-min_wr)*exp(prof_wr*(t_reduce-c_ref)) + min_wr - refwr*exp(prof_wr*(c_cut-c_ref))) &
        / (1.-exp(prof_wr*(c_cut-c_ref)))

   endif

end function rate_1step


real function rate1_2step (ya, yx, theta)

    real, intent(in)  :: ya
    real, intent(in)  :: yx
    real, intent(in)  :: theta

    real :: y1
    real :: y2
    real :: t_reduce

    y1=ya
    if(ya.lt.0.) y1=0.
    if(ya.gt.1.) y1=1.

    y2=yx
    if(yx.lt.0.) y2=0.
    if(yx.gt.1.) y2=1.

    t_reduce=theta
    if(theta.lt.0.) t_reduce=0.
    if(theta.gt.1.) t_reduce=1.

    rate1_2step = 0.

end function rate1_2step


real function rate2_2step (yx, theta)

    real, intent(in)  :: yx
    real, intent(in)  :: theta

    real :: y
    real :: t_reduce

    y=yx
    if(yx.lt.0.) y=0.
    if(yx.gt.1.) y=1.

    t_reduce=theta
    if(theta.lt.0.) t_reduce=0.
    if(theta.gt.1.) t_reduce=1.

    rate2_2step = 0.

end function rate2_2step

end module m_chemistry