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Continuously composed rotations. (English) Zbl 1194.51016

The author proves the following: The result of applying a continuously composed family of rotations of the complex plane with smooth center path \(c:[0,1]\to{\mathbb C}\) and angular velocity function \(\omega:[0,1]\to{\mathbb R}\) is either a translation or a rotation, depending on whether \(\Theta=\int_{0}^{1}\omega(\tau)d\tau\) is, or is not in \(2\pi{\mathbb Z}\). Moreover, the author exhibits three examples of continuously composed rotations resulting in translations.

MSC:

51M04 Elementary problems in Euclidean geometries
65T50 Numerical methods for discrete and fast Fourier transforms
42A16 Fourier coefficients, Fourier series of functions with special properties, special Fourier series