Adding custom properties to response plot (e.g. settling time, peak response etc.)

Hey everyone,

I have a simple model of a state-space system and I'd like to examine its response to initial conditions.

One of the things I'd like to show is a kind of "settling time", but not the kind we all know and love (ha). I want to show the first point at which the graph goes below a certain value (1% of the starting point, for what it's worth. It's a descending graph, of course).

Now, had this been a common thing to show, I'd have the option to display is through right click-->properties, but it's not.

So my question is - how do I go about doing this? I basically need to do three things:

1. adding a marker to the plot at the specific point where the graph goes below a certain value (call it m)

2. plotting a horizontal line (at m) that goes from the y-axis to the graph line (but doesn't cross it)

3. plotting a vertical line that goes from the x-axis up to the graph (but doesn't cross it)

If you guys have any ideas/tips, please share! Any kind of help would be greatly appreciated.

[Guy Lalkin]

So after doing a little more digging through the 'plot' documentation, I've come up with this:

h=initial(sys,x0,t);
ix=find(h<=m,1);
initial(sys,x0,t)
hold on
% plot horizontal line, vertical line and marker
plot([0 t(ix)],[m m],'b--',[t(ix) t(ix)],[0 m],'b--',...
     t(ix),0.02*(pi/2),'ro','MarkerSize',5,'MarkerFaceColor','r')

Is this a good solution? I feel it's kind-of "dirty", if you know what I mean, but it gets the job done. If anyone has any other suggestions, you're more than welcome to reply!