I wrote you a note on control theory

Next Tuesday, I will spend like, a quarter of an hour talking a little bit more about this. Then we start on difference equations.

I took the old 2018 note on control theory, and updated it to a draft 2019 version (please YELL at me if something needs to be changed):

• I kept page 1 although we haven't gotten to that yet. You may disregard that for the moment.
• page 2: take footnote 3 very lightly.
• page 3: I stuffed in references to the old handwritten notes, with hyperlink (yeah, do not work on paper). 
  The 3rd 2018 note is less needed. 
• Examples now have letter-enumeration, as the handwritten notes have numbers ...
• page 6: in place of yesterday's not-so-good example. 
• page 10: sensitivity moved here, and today's example - in CV formulation - is typeset.
• page 11: at the end, delimiting curriculum. Eagle-eyes might spot a new headline about scrap values. That is nothing new, I put it in just because somebody asked.