MATLAB中的冒号（:）

(2012-03-21 07:37:30)

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分类： MATLAB

1.冒号的作用

产生矢量，阵列标注以及for-loop迭代子

冒号是MATLAB中最有用的操作符之一。它使用下述规则来创建有规则的空间矢量：

`j:k`	is the same as `[j,j+1,...,k]`, or empty when `j > k`.
`j:i:k`	is the same as `[j,j+i,j+2i, ...,j+m*i]`, where `m = fix((k-j)/i)`, for integer values. For information on the definition of `j:i:k` with floating-point values, see Technical Solution 1-4FLI96. This syntax returns an empty matrix when `i == 0`, `i > 0` and `j > k`, or `i < 0` and `j < k`.

如果你指定单标量阵列，MATLAB将j:i:k 解释为 j(1):i(1):k(1).

You can use the colon to create a vector of indices to select rows, columns, or elements of arrays, where:

`A(:,j)`	is the `j`th column of `A`.
`A(i,:)`	is the `i`th row of `A`.
`A(:,:)`	is the equivalent two-dimensional array. For matrices this is the same as `A`.
`A(:,j:k)`	is `A(:,j), A(:,j+1),...,A(:,k)`.
`A(:,:,k)`	is the `k`th page of three-dimensional array `A`.
`A(i,j,k,:)`	is a vector in four-dimensional array `A`. The vector includes `A(i,j,k,1)`, `A(i,j,k,2)`, `A(i,j,k,3)`, and so on.
`A(:)`	is all the elements of `A`, regarded as a single column. On the left side of an assignment statement, `A(:)` fills `A`, preserving its shape from before. In this case, the right side must contain the same number of elements as `A`. 注：上述内容来自于MATLAB帮助文档

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