原文：http://answers.yahoo.com/question/index?qid=20080610030617AAymrnC
Matlab works on first non-singleton dimension of multidimensional matrices in some builtin functions. But how is it defined?
matlab的一些函数经常对于多维度矩阵中第一个non-singletion维度起作用，可是non-singleton到底是什么含义呢？
A singleton dimension is one with size = 1. For example,
Singleton维度就是该维度下的size值为１，比如
if Z is a 1-by-2-by-3-by-4 four-dimensional array, then the second dimension is the first non-singleton dimension.
Ｚ是一个1*2*3*4的四位矩阵，则它的第二维为第一个non-singleton维度
In Matlab, arrays have at least two dimensions, so to represent a vector you use a N-by-1 or 1-by-N dimensional array. Because it is inconvenient to keep transposing these things to get the non-singleton dimension in the right place, a lot of library functions
will figure it out automatically - using the first non-singleton dimension.
matlab中，数组至少有两个维度。所以表达一个矢量时，可使用N*1或1*N维度的数组。后面的好绕口，查找些资料在翻译