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	jpye	2569	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;