From an earlier post:
With you there, spec.
First got introduced to the idea (40+ years ago) as it related to a rather complex formula for determining some OPA characteristic (don't remember what except it was an oscillator application).
At the front end of the formula "
i" (or "
j" in electronics) was introduced and then later it was re-introduced such that the result was
i squared, thus resulting in the
entire formula being multiplied by -1. I asked the professor; "Why the imaginary ruse? How about just put the whole formula in parentheses with a -1 in front?". Turned out to have something to do with phase. There were other ways to get the answer.
The theoretical electronics I leave to the engineers; I'm a technician...
.