English
For every n ∈ ℤ and x ∈ AddCircle(T), the value of the Fourier monomial is the exponential e^{2π i n x / T} on the circle, i.e., f_n(x) = e^{2π i n x / T}.
Русский
Для каждого n ∈ ℤ и x ∈ AddCircle(T) значение мономиалы Фурье равно экспоненте e^{2π i n x / T} на окружности: f_n(x) = e^{2π i n x / T}.
LaTeX
$$$f_n(x) = e^{\\frac{2\\pi i\,n\,x}{T}}, \\quad n \\in \\mathbb{Z}, \\ x \\in AddCircle(T).$$$
Lean4
@[simp]
theorem fourier_apply {n : ℤ} {x : AddCircle T} : fourier n x = toCircle (n • x :) :=
rfl