% RK4PLOT.M 
% This estimates and plots numerical solutions to an ODE using a 4th order 
% Runge-Kutta method. It calls the function RK4.M. Both M-files get initial 
% information from INITN.M. 

cla 
axis(initax); 
tmatr=[]; xmatr=[]; tsize=[]; tvec=[]; xvec=[]; 
tmax=t0; xmin=x0; xmax=x0; tspan=[t0,tf]; 
for j=1:max(size(hvec)) 
   [t,x]=rk4(ftx,tspan,x0,hvec(j))
   t=t'; x=x'; 
	if min(x)>-inf 
		if xmin>min(x) 
			xmin=min(x); 
		end 
	end 
	if max(x)<inf 
		if xmax<max(x) 
			xmax=max(x); 
		end 
	end 
	tsize=[tsize,max(size(t))]; 
	[u,v]=size(tmatr); 
	if v>max(size(t)) 
		t=[t,zeros(1,v-max(size(t)))]; 
	else 
		tmatr=[tmatr,zeros(u,max(size(t))-v)]; 
	end 
	tmatr=[tmatr;t]; 
	[u,v]=size(xmatr); 
	if v>max(size(x)) 
		x=[x,zeros(1,v-max(size(x)))]; 
	else 
		xmatr=[xmatr,zeros(u,max(size(x))-v)]; 
	end 
	xmatr=[xmatr;x]; 
	if j==minhindex 
		tmax=max(t); 
		tvec=t; 
		xvec=x;
	end 
end 
axis([t0,tf,xmin,xmax]); 
ax=axis; 
plotlabel=['RK4: x'' = ',ftx,',  h = [',num2str(hvec),']']; 
slopef(ftx,N); 
%hold on
for j=1:max(size(hvec)) 
	plot(tmatr(j,1:tsize(j)),xmatr(j,1:tsize(j))) 
end 
xlabel(plotlabel) 
hold off 
ax=[t0,tf,xmin,xmax]; 
clear y