mathlib documentation

analysis.special_functions.trigonometric.chebyshev

Multiple angle formulas in terms of Chebyshev polynomials #

The n-th Chebyshev polynomial of the first kind evaluates on cos θ to the value cos (n * θ).

cos (n * θ) is equal to the n-th Chebyshev polynomial of the first kind evaluated on cos θ.

The n-th Chebyshev polynomial of the second kind evaluates on cos θ to the value sin ((n+1) * θ) / sin θ.

sin ((n + 1) * θ) is equal to sin θ multiplied with the n-th Chebyshev polynomial of the second kind evaluated on cos θ.