Welcome to Nonlinear World!

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Here are introductory articles on the nonlinear world.

From pendulum to soliton (GIF images, texts in Japanese)
A pendulum is a typical nonlinear system that we encounter in our life frequently. This article shows how the sine-Gordon equation -- a model equation of soliton phenomena -- emerges out of this simple mechanical system.

Many faces of solitons
Solitons can be observed in many equtions. The profile of solitons are diverse and reflect the equation. This article presents many faces of solitons with texts and movies.