Riemann's continuous non-differentiable function

F_{φ} (x) = \sum_{n = 1}^{∞} \frac{\sin (n^{2} x + φ)}{n^{2}}, x \in ℝ

The original function is only for the case of $φ = 0$ , but sweeping the phase of every harmonic looks cool in an animation so...

More about this function: S1631073X19302171.pdf