Phase could be the thing, beats me, it’s been a while. Negative resistance is also another one of those concepts that pop up now and then, specifically negative differential resistance.
Oh god, it’s been a long time since I took Vibrations and Waves, but I still remember filling notebook after notebook with Fourier transform equations.
Negative frequency is a concept in signal processing, and many other domains.
https://en.wikipedia.org/wiki/Negative_frequency
Phase could be the thing, beats me, it’s been a while. Negative resistance is also another one of those concepts that pop up now and then, specifically negative differential resistance.
Oh god, it’s been a long time since I took Vibrations and Waves, but I still remember filling notebook after notebook with Fourier transform equations.
I mean, the signs* are right there in the article
*something something sines