In theory, semiparametric functional coefficient quantile regression has less hypothesis and more extensive application in order to explain economic phenomena accurately. 半參數變係數分位數回歸模型，在理論上其假設前提條件限制比較少，在應用上具有很好的靈活性和很廣的適用空間，能夠更好地解釋現實經濟問題。
In this paper, we mainly discuss nonparametric and semiparametric functional coefficient quantile regressions, their estimation methods and applications. 在本文中，主要討論了非參數和半參數變係數分位數回歸模型的估計及其應用。
An important case is the linear homogeneous second-order differential equation with constant coefficients. 一種重要的情形是常係數二階線性齊次微分方程。
