Todd Fatheree wrote:
....
Well, I'm not an EE, but where I went to engineering school, sqrt(-1) = i.
I also can't find a reference for it via Google. Do you have a reference
for it? I'm not saying you're wrong, just that I've never heard of it, and
I've been exposed to enough EE back in my school daze to know what reactance
is and power factor and some of that cool polyphase stuff.

j for sqrt(-1) is quite common in EE, probably more so than i which is
more prevalent in mathematics or physics. One reason is that "i" is so
often used for current in EE.

As for reference, let's see...

Ok, here

T(jw) = G(jw)/(1 + G(jw)) -- ~1, |G(jw)| 1 Eq (8-60)

Closed-loop transfer function frequency response.

Feedback Control Systems, Phillips & Harbor, Prentice-Hall. ISBN
0-13-313917-4