simplify(dsolve('Dy=-x/y','y(0)=5','x'))
f=@(x) (-x^2+25)^(1/2);
dydx=@(x,y) -(x/y);
[x1,y1]=eulode(dydx, [0 1],5,.5);
[x2,y2]=eulode(dydx,[0 1],5,.1);
[x3,y3]=eulode(dydx,[0 1],5,.01);
disp([x1,y1])
disp([x2,y2])
disp([x3,y3])
plot(x1,y1,'k',x2,y2,'b',x3,y3,'g','linewidth',2)
figure(2)
fplot(f,[0 5],'linewidth',2,'k')