突然ですが、今回は IB Math AA のシラバスに含まれている Rational Function（有利関数）についてまとめます。 一次関数や三角関数などに比べて rational function はグラフの概形をイメージしづらく、あまり馴染みがない人もいると思いますが、実は IB Final で出題さ ...

in [MAT151 of 2023](https://github.com/TheNoteTaker/2023_spring_mat151/blob/main/units/unit_03_function_transformations_quadratic_polynomial_and_rational_functions ...

Extending a result of Khavinson and $\acute{S}wi\cedil{a}tek$ (2003) we show that the rational harmonic function $\overline {r(z)} - z$, where r(z) is a rational function of degree n > 1, has no more ...

For a rational matrix function Φ with poles outside the unit circle, we estimate the degree of the unique superoptimal approximation 𝒜Φ by matrix functions analytic in the unit disk. We obtain sharp ...