test/link/pendulum_wLINK.a4c

REQUIRE "ivpsystem.a4l";
REQUIRE "atoms.a4l";
IMPORT "johnpye/extpy/extpy";
IMPORT "johnpye/solve";

MODEL pendulum;
    x IS_A delta_distance; y IS_A delta_distance;
	r IS_A distance;
	theta IS_A angle;
	-y = r*cos(theta);
	x = r*sin(theta);

	m IS_A mass;
	v_x IS_A speed; v_y IS_A speed;
	a_x	IS_A acceleration; a_y IS_A acceleration;
	g IS_A acceleration;

	t IS_A time;

	(* equations of motion *)
	Fc IS_A force;
	+Fc*cos(theta)-m*g = m*a_y;

	-Fc*sin(theta) = m*a_x;
	

METHODS
METHOD specify;
	FIX r, m, g, x, t;
	FIX v_x;
END specify;

METHOD default_self;
	y := -sqrt(3)/2*(1{m});
	x := 0.5 {m};
	r := 1 {m};
	v_y := 0 {m/s};
	v_x := 0 {m/s};
END default_self;

METHOD values;
	t := 0 {s};
	r := 1 {m};
	m := 1 {kg};
	g := 9.8 {N/kg};
END values;

METHOD set_ode; (* LINK syntax to set the ode relationships in the procedural part *)
	DER(v_x, x );
	DER(a_x,v_x);
	DER(v_y, y );
	DER(a_y,v_y);
	INDEPENDENT t;
	(* Note: In this case there is no longer the need to create two more variables v_x1 and v_y1, even though they belong to two derivative chains with different types, because their types are taken from the link structure rather than from the varaible children *)

END set_ode;

METHOD set_obs;
	x.obs_id :=1;
	y.obs_id :=2;
END set_obs;

METHOD on_load;
	RUN default_self;
	RUN reset;
	RUN specify;
	EXTERNAL solve(SELF);
	EXTERNAL solve(SELF);
	RUN set_obs;
	RUN set_ode;
END on_load;

END pendulum;
1	REQUIRE "ivpsystem.a4l";
2	REQUIRE "atoms.a4l";
3	IMPORT "johnpye/extpy/extpy";
4	IMPORT "johnpye/solve";
5
6	MODEL pendulum;
7	x IS_A delta_distance; y IS_A delta_distance;
8	r IS_A distance;
9	theta IS_A angle;
10	-y = r*cos(theta);
11	x = r*sin(theta);
12
13	m IS_A mass;
14	v_x IS_A speed; v_y IS_A speed;
15	a_x IS_A acceleration; a_y IS_A acceleration;
16	g IS_A acceleration;
17
18	t IS_A time;
19
20	(* equations of motion *)
21	Fc IS_A force;
22	+Fccos(theta)-mg = m*a_y;
23
24	-Fcsin(theta) = ma_x;
25
26
27	METHODS
28	METHOD specify;
29	FIX r, m, g, x, t;
30	FIX v_x;
31	END specify;
32
33	METHOD default_self;
34	y := -sqrt(3)/2*(1{m});
35	x := 0.5 {m};
36	r := 1 {m};
37	v_y := 0 {m/s};
38	v_x := 0 {m/s};
39	END default_self;
40
41	METHOD values;
42	t := 0 {s};
43	r := 1 {m};
44	m := 1 {kg};
45	g := 9.8 {N/kg};
46	END values;
47
48	METHOD set_ode; (* LINK syntax to set the ode relationships in the procedural part *)
49	DER(v_x, x );
50	DER(a_x,v_x);
51	DER(v_y, y );
52	DER(a_y,v_y);
53	INDEPENDENT t;
54	(* Note: In this case there is no longer the need to create two more variables v_x1 and v_y1, even though they belong to two derivative chains with different types, because their types are taken from the link structure rather than from the varaible children *)
55
56	END set_ode;
57
58	METHOD set_obs;
59	x.obs_id :=1;
60	y.obs_id :=2;
61	END set_obs;
62
63	METHOD on_load;
64	RUN default_self;
65	RUN reset;
66	RUN specify;
67	EXTERNAL solve(SELF);
68	EXTERNAL solve(SELF);
69	RUN set_obs;
70	RUN set_ode;
71	END on_load;
72
73	END pendulum;