null adj. 1.无效力的,无束缚力的。 2.无效的,无用的,无益的;无价值的。 3.没特征[个性]的,没表情的。 4.〔罕用语〕不存在的,没有的;零(位)的;空的。 n. 【数学】零,零位;空;【无线电】零讯号,微弱讯号。 a null indicator 零示器;零位指示器。 the null method 衡消法。 null and void 【律】无效;失效(This check is null and void. 本支票无效)。 vt. 使无效。
It redefines the between - class scatter by adding a weight function according to the between - class distance . therefore , it can separate the classes as much as possible . at the same time , it projects the between - class scatter into the null space of the within - class scatter that contains the most discriminant information 新方法重新定义了样本类间离散度矩阵,在原始定义的基础上增加一个由类间距离决定的可变权函数,使得在选择投影方向时,能够更好地分开各个类的样本。
First , we do not know what kind of bifurcation will happen in advance , it is difficult to choose what kind of regular extended system for detecting them . second , if there are higher order singularities , even the multi - dimensional null space , one parameter is not enough for establishing a regular extended system 首先考虑单参数非线性问题,如果参数的个数足够多,在延拓过程中通过求解各种正则的扩展系统可以求出方程解枝上存在的各种高阶奇异点,例如高阶折叠点、横截式分歧点、音叉式分歧点等。