[sdiy] SDIY MATH GOALS--need real help!

[David G. Dixon]

In my last post in answer to Dan Snazelle's query, I stupidly said the
following:

> Your question is a good one, because it leads directly to the most
> fundamental idea in differential calculus; namely, the "central limit
> theorem".

Of course, what I meant was the "mean value theorem".  (The CLT is a
statistics thing.)  I was actually in the middle of soldering up a new VCO
board design at the time Dan's original post came through, and I must have
been "hopped up" on flux fumes!

> This says that a function evaluated at x + Delta-x minus that
> function evaluated at x, all over Delta x, approaches the differential
> df/dx as Delta-x approaches zero.  

Of course, this is really the mean value theorem backwards, and is really
just the definition of the first derivative (thanks again, Sir Isaac!).