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Fourier Series

Every repeating wave is a stack of pure sines. Add harmonics one at a time and watch a square wave assemble itself — bumps, ringing, and all.

Targets repeat every 2π. At jumps the target reads 0 — the midpoint the series converges to.

Try this

  1. Take the square wave from 1 harmonic to 25 and watch the corners sharpen.
  2. Toggle parts on and see which sine does the heavy lifting.
  3. Drag the probe into a jump and compare target vs sum.

How Fourier series work here

Any periodic wave can be written as a sum of sines and cosines — one per harmonic. This lab uses the exact textbook formulas for three classic waves, so each harmonic you add is the mathematically correct next term.

Near a jump, the sum always overshoots by about 9% no matter how many harmonics you add. That is the Gibbs phenomenon — a theorem about partial sums, not a rendering bug. The marker shows it; the lab never hides it.

Hear the math behind the music

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