# What is the moment when all oscillators aligned to make a jump called?

Say we have a square wave and its Fourier series. When the wave doesn't jump, its oscillators aren't aligned:

But if they are aligned, the wave will jump:

What is this moment called? They might not be necessary in the same angle, and I don't think "resonating together" is correct, since they have different frequencies. What is it called when all oscillators aligned to make a jump?

Meta discussion: Why are questions asking for terms off-topic?

• Coincidence of zero crossings and same sign of derivation? – Max Mar 20 '18 at 9:45
• too long........... – Ooker Mar 20 '18 at 10:49
• Try searching on "gibbs phenomenon". Those are the little squiggles you see on the flat part of your square wave. – Cedron Dawg Mar 20 '18 at 12:04

Phasor Alignment : The individual frequency component phasors of the square wave are aligning, but I don't think this is a well-defined (or previously-defined) term.

I think the word/phrase you are looking for is "discontinuity" / "discontinuity in the source signal". Although a jump is always a discontinuity, a discontinuity is not always a jump. When it isn't a jump, it is known as a pluggable discontinuity, i.e. you can define a value to plug a hole. The sinc function at zero is an example of this. So to be more specific you would say "an unpluggable discontinuity".

Whether a series of continuous functions could converge to a discontinuous function was a question that led to some very serious, and non-intuitive, math.

As far as I know, there is no word to describe the state of the components at this moment. The closest word I can think of is a secondary meaning of "concordance" = "agreement".

Hope this helps.

Ced

• I find out that the term is actually removable discontinuity. But yes, I'm looking for a word of the state of the components. If you think there is no word for this, I think this question is better suited in English Language & Usage – Ooker Mar 20 '18 at 12:05

It is the time of maximum constructive interference of the derivatives of the harmonics. That's a physics term, but widely known.

One can simply say the oscillators are in sync, or synchronized. Some other synonyms of the synchronization in English are: conjunction co-occurrence, concurrence, coincidence, coexistence, simultaneity, contemporaneity, concomitance, synchronicity, synchrony