search_2D Subroutine

    subroutine search_2D(array, nlow, value)
        !! search by bisection for 1D array
        
        !> 2D array to search. Only searches 1st column
        real(kind=wp),       intent(in)  :: array(:, :)
        !> Index of found index
        integer(kind=int64), intent(out) :: nlow
        !> Value to find in the array.
        real(kind=wp),       intent(in)  :: value
        
        integer :: nup, middle
        
        nup = size(array, 1)
        nlow = 1
        middle = int((nup+nlow)/2.)

        do while((nup - nlow) > 1)
            middle = int((nup + nlow)/2.)
            if(value > array(middle, 1))then
                nlow = middle
            else
                nup = middle   
            end if
        end do
    end subroutine search_2D