[mesa-users] grad_mu

Martin C. martincs14 at gmail.com
Thu Aug 4 16:33:47 EDT 2016

Hi all,

How might I obtain/compute grad_mu in MESA?
There is s% gradL_composition_term, which according to

 real(dp), pointer :: gradL_composition_term(:)
         ! in the literature, this term is often written as phi/delta*gradmu

But I would like just grad_mu which is dlnmu/dlnP I think.
Can I calculate it with a routine like this or is this nonsense?

    subroutine calc_my_gradmu(my_gradmu, s)
        implicit none
        integer :: i
        type (star_info), pointer :: s
        real(dp) :: my_gradmu(s% nz), dP(s% nz), dmu(s % nz)

        do i = 2, s% nz - 1
            dP(i) = s% P(i-1) - s% P(i+1)
            dmu(i) = s% mu(i-1) - s% mu(i+1)
        end do

        dP(1) = s% P(1)- s% P(2)
        dP(s% nz) = s% P(s% nz-1) - s% P(s% nz)

        dmu(1) = s% mu(1)- s% mu(2)
        dmu(s% nz) = s% mu(s% nz-1) - s% mu(s% nz)

        do i = 1, s% nz
            my_gradmu(i) = s% P(i) / s% mu(i) * dmu(i) / dP(i)
        end do
    end subroutine calc_my_gradmu



Martin C.
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