你说的列到底是指什么？
a=[2 3;3 6;4 9]是三行两列，
a =
2 3
3 6
4 9
如果你要得到b =
4 9
则程序为
a=[2 3;3 6;4 9] 或者 a=[2 3;3 6;4 9]
b=max(a) b=max(a,[],1)
如果要得到
b =
3
6
9
则程序为：
a=[2 3;3 6;4 9]
b=max(a,[],2)
max具体用法可以见使用help max命令
help max
MAX Largest component.
For vectors, MAX(X) is the largest element in X. For matrices,
MAX(X) is a row vector containing the maximum element from each
column. For N-D arrays, MAX(X) operates along the first
non-singleton dimension.
[Y,I] = MAX(X) returns the indices of the maximum values in vector I.
If the values along the first non-singleton dimension contain more