Don't Ask Me Questions

I get up this morning, and after buying my usual supplements of penis pills and donkey pornography, mortgage my non-existent house, pour some money into pump-and-dump stocks, I come across this email sitting in my inbox:

-------- Messaggio Originale --------
Oggetto: I am dumb and I need your help
Data: Thu, 8 Mar 2007 21:05:26 -0500

I'm not so smart and something's giving me some trouble.

I'm trying to have my discrete-time control system tune itself automatically so that it matches some sort of desired step response. The tuned value is sort of like the control cost in an optimal LQR controller. One value for the SISO case. I numerically evaluate the frequency response of the controller for some value of the cost, then I multiply it by the DFT of a step (actually a long-period square wave since it's a discrete-time system). I compare the resulting inverse DFT to the step response I want. I tune the cost by minimizing the squared error between the predicted step response and my desired step response. Great, it works. Only for my controller it is actually more useful to tune the response to a zero reference and a nonzero initial condition.

My question is, how can I use my computed frequency response to predict the settling response? Am I doing this all the wrong way?
-------------------------------------

It's too early for me to think, so I send him some stupid response:

-------- Messaggio Originale --------
Oggetto: Re: I am dumb and I need your help
Data: Fri, 9 Mar 2007 07:38:51 +0100

I'll answer this when I get to work, but first off, no one who sends an email titled "I'm dumb and I need help" includes the acronyms LQR, SISO, DFT, blah.

When I read the title, I was SURE you were emailing me from the ibook of a girl in whose apartment you found yourself and after doing her while she was sleeping you needed to extricate yourself so you did the only thing you knew how, which was email me. So sure. Know that I really don't mind your weird segues into just asking whats really on your mind, I just sometimes wish you had the guts to get it out.
-------------------------------------

Then an hour later I realize what he really meant when he emailed me, so I write him again.

-------- Messaggio Originale --------
Oggetto: Re: I am dumb and I need your help
Data: Fri, 09 Mar 2007 02:53:38 -0500

Hey,
Sorry I didn't figure out what you meant earlier, I had just gotten up and I was sleepy. Here's what I think you should do. First, find a bowl of warm water and a wash cloth. I figure you're in your own apartment (otherwise how did you get like this?) so it should be easy. Ok, now start massaging the warm water around your neck, and whatever else is exposed. The trick here is to relax the muscles so that you don't damage anything. Now we're going to do it in two steps, the first step is the chin and the second is the back of the head.

Tuck your chin in to your neck, like you're trying to be a turtle. Now exhale deeply and pull. The warm water should alleviate some of the stubble burn, but you might feel it tomorrow. Now that this part is done, most people (well, whoever else gets themselves in this situation anyway) think it's all over and jerk back, but the back of the head can still do a lot of damage. Inhale, (I bet that part sucks, but at least now your mouth is free) then exhale again deeply (more warm water if you want) and do one final pull, pushing with your hands against the backs of your legs if you need to.

There, now your head should be out of your ass. I'm just amazed you could compose an email in that position!