reshape把指定的矩阵改变形状，但是元素个数不变， 

例如，行向量： 
a = [1 2 3 4 5 6] 

执行下面语句把它变成3行2列： 
b = reshape(a,3,2) 

执行结果： 
b = 
1 4 
2 5 
3 6

若a=[1 2 3 
4 5 6 
7 8 9]

使用reshpe后想得到b=[1 2 3 4 5 6 7 8 9]

只需要将a转置一下就可以了： 
b=reshape(a\',1,9)

－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－

matlab中的解释如下：

RESHAPE Change size.
    RESHAPE(X,M,N) returns the M-by-N matrix whose elements
    are taken columnwise from X. An error results if X does
    not have M*N elements.

    RESHAPE(X,M,N,P,...) returns an N-D array with the same
    elements as X but reshaped to have the size M-by-N-by-P-by-...
    M*N*P*... must be the same as PROD(SIZE(X)).

    RESHAPE(X,[M N P ...]) is the same thing.

    RESHAPE(X,...,[],...) calculates the length of the dimension
    represented by [], such that the product of the dimensions 
    equals PROD(SIZE(X)). PROD(SIZE(X)) must be evenly divisible 
    by the product of the known dimensions. You can use only one 
    occurrence of [].

    In general, RESHAPE(X,SIZ) returns an N-D array with the same
    elements as X but reshaped to the size SIZ. PROD(SIZ) must be