Try to make scilab do the note1b.txt for ti89

1. Solve y' = y(2-y); y(0) = 3
	a. Rewrite equation as y' = f(t,y) so f(t,y) = y(2-y) and define f
	scilab code
		function ydot = f(t,y)
		ydot = y*(2-y);
		endfunction
	b. Use ode to solve the system. We will use [0,5] as the range of t
		t = 0:0.1:5; y0 = 3; t0 = 0; 
		y = ode(y0, t0, t, f); 
	y is the numerical solution. you can see it best by typing y' where
	prime is transpose and not a derivative.
	c. plot the solution
		plot(t,y,"r--x")

Variation, several solutions, each plot adds more to the graph
		plot(t, ode(1, t0, t, f)

2. Add the slopefield to the graph. (called the direction field in
the text, but actually is a vector field.)
		The command is champ(xgrid, ygrid, fx, fy, arfact=0)

		xgrid = 0:0.5:5; ygrid = 0:0.5:3
		size(xgrid) gives 1 n size(ygrid) gives 1 m
		fy = ones(n,m);
		for i = 1:n, for j = 1:m, fy = f(xgrid(i), ygrid(j)); end, end;
		champ(xgrid, ygrid, fx, fy, arfact=0)

3. Scilab can't solve ode's analytically. But it can check a solution
by ploting.
		ytrue = solution(t)
		plot(ytrue - y)

	Use clf() to restart the graph.