矩阵或向量参数的冒号运算符(:)的行为 [英] behavior of colon operator (:) with matrix or vector arguments

问题描述

我们都知道matlab冒号运算符可以创建线性序列，即

We all know the matlab colon operator to create a linear sequence, i.e.

1:5 = [1 2 3 4 5]

现在，我发现冒号运算符的参数也可以应用于向量或矩阵.但是我不理解后面的定义.

Now I found that the arguments of the colon operator can also be applied to vectors or matrices. However I do not understand the definition behind.

示例

[1 2 3 4]:5 == [1 2 3 4 5]

[1 2; 3 4]:3 == [1 2 3]

这是为什么?

第二个参数也可以是向量或矩阵.

The second argument can be vector or matrix as well.

最终我想了解

1:2:3:4:5 

在matlab和[1 5]中完全合法！

which is fully legal in matlab and [1 5] by the way!

注意1:2:3:4:5:6保持关联，即被解析为((1:2:3):4:5):6.

Note 1:2:3:4:5:6 is left associative i.e. parsed as ((1:2:3):4:5):6.

那么带有矩阵/矢量参数的冒号运算符的行为是什么?

So what is the behavior for the colon operator with matrix/vector arguments?

更正了左联想性的陈述.

corrected the statement of left associativity.

推荐答案

文档对于冒号运算符说:

如果指定非标量数组，则MATLAB会将j:i:k解释为j(1):i(1):k(1).

If you specify nonscalar arrays, MATLAB interprets j:i:k as j(1):i(1):k(1).

您的第一个示例被解释为1:3，第二个示例被解释为1:5

Your first example is interpreted as 1:3, the second as 1:5

具有两个以上:的表达式被解析为左关联:

Expressions with more than two : are parsed left-associative:

a:b:c:d:e==(a:b:c):d:e

.

    >> 1:2:3:4:5

ans =

     1     5

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