This module helps drawing grids and plotting functions.

`type skeleton`

The abstract skeleton for grids, axes and functions

`val mk_skeleton : int -> int -> Num.t -> Num.t -> skeleton`

`mk_skeleton w h dx dy` builds a skeleton of width `w` and height `h`, each cell being `dx` units wide and `dy` units high.

`type labels = int -> Num.t -> Picture.t option`
`type ticks = (Num.t * Pen.t) option`
`type drawing =`

1. `| Stepwise`
2. `| Normal`

`val draw_grid : ?hdash:(int -> Dash.t) -> ?vdash:(int -> Dash.t) -> ?hpen:(int -> Pen.t) -> ?vpen:(int -> Pen.t) -> ?color:Color.t -> skeleton -> Command.t`
`val draw_axes : ?hpen:Pen.t -> ?vpen:Pen.t -> ?hlabel:labels -> ?vlabel:labels -> ?ticks:ticks -> ?closed:bool -> ?hcaption:Picture.t -> ?vcaption:Picture.t -> skeleton -> Command.t`
`val draw_simple_axes : ?hpen:Pen.t -> ?vpen:Pen.t -> string -> string -> skeleton -> Command.t`
`val draw_func : ?pen:Pen.t -> ?drawing:drawing -> ?style:Path.joint -> ?dashed:Dash.t -> ?color:Color.t -> ?label:(Picture.t * Command.position * int) -> ?from_x:int -> ?to_x:int -> (int -> float) -> skeleton -> Command.t`