说明：  Fisher线性判别是线性分类算法中最基本的一种算法，其基本思想是将d维空间中的样本投影到一条最易于分类的投影线上，再进行分类。本文将用使用matlab实现Fisher线性判别算法，并给出４种阈值选择的方法。
(Fisher Linear Discriminant is a linear classification algorithm as a basic algorithm, its basic idea is to d-dimensional space of the samples are projected onto one of the most easily classified projector online, and then classified. This article will use matlab to achieve Fisher Linear Discriminant algorithm, and gives four kinds of threshold selection method.)