repeat_init Function

    type(repeat) function repeat_init(prim, c, la, lb) result(out)
        !! Initialise the Repeat modifier for a SDF.
        
        !> SDF to modify
        class(sdf_base), target :: prim
        !>
        type(vector),  intent(IN) :: la
        !> 
        type(vector),  intent(IN) :: lb
        !>
        real(kind=wp), intent(IN) :: c

        out%c = c
        out%la = la
        out%lb = lb
        out%prim => prim

        out%optProps = prim%optProps

        out%layer = prim%layer
        out%transform = identity()

    end function repeat_init