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(*
Polar plot demo.
Copyright (C) 2008, 2009 Hezekiah M. Carty
This file is part of PLplot.
PLplot is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published
by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
PLplot is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with PLplot; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*)
open Plplot
let pi = atan 1.0 *. 4.0
(*--------------------------------------------------------------------------*\
* main
*
* Generates polar plot, with 1-1 scaling.
\*--------------------------------------------------------------------------*)
let main () =
let dtr = pi /. 180.0 in
let x0 = Array.init 361 (fun i -> cos (dtr *. float_of_int i)) in
let y0 = Array.init 361 (fun i -> sin (dtr *. float_of_int i)) in
(* Parse and process command line arguments *)
plparseopts Sys.argv [PL_PARSE_FULL];
(* Set orientation to portrait - note not all device drivers
* support this, in particular most interactive drivers do not *)
plsori 1;
(* Initialize plplot *)
plinit ();
(* Set up viewport and window, but do not draw box *)
plenv (-1.3) 1.3 (-1.3) 1.3 1 (-2);
for i = 1 to 10 do
(* Draw circles for polar grid *)
let r = 0.1 *. float_of_int i in
plarc 0.0 0.0 r r 0.0 360.0 0.0 false;
done;
plcol0 2;
for i = 0 to 11 do
let theta = 30.0 *. float_of_int i in
let dx = cos (dtr *. theta) in
let dy = sin (dtr *. theta) in
(* Draw radial spokes for polar grid *)
pljoin 0.0 0.0 dx dy;
let text = string_of_int (int_of_float (floor (theta +. 0.5))) in
(* Write labels for angle *)
let offset =
if theta < 9.99 then
0.45
else if theta < 99.9 then
0.30
else
0.15
in
(* Slightly off zero to avoid floating point logic flips at 90 and
270 deg.*)
if dx >= -0.00001 then
plptex dx dy dx dy (-.offset) text
else
plptex dx dy (-.dx) (-.dy) (1.+.offset) text
done;
(* Draw the graph *)
let x =
Array.init 361 (fun i -> x0.(i) *. sin (dtr *. float_of_int (5 * i)))
in
let y =
Array.init 361 (fun i -> y0.(i) *. sin (dtr *. float_of_int (5 * i)))
in
plcol0 3;
plline x y;
plcol0 4;
plmtex "t" 2.0 0.5 0.5 "#frPLplot Example 3 - r(#gh)=sin 5#gh";
(* Close the plot at end *)
plend ();
()
let () = main ()
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