J:方便的输入矩阵的方法吗? [英] J: Handy method to enter a matrix?

问题描述

我有一个写在纸上的 n -by- m 矩阵，我想在J中对其进行计算.
我可以输入这样的矩阵( n = 3， m = 3):

I have a n-by-m matrix written at paper and I want to make calculations on it in J.
I can enter matrices like that (n = 3, m = 3):

   A =: 3 4 $ 1 3 2 4 7 8 1 2 2 0 0 1

问题是如何输入这样的矩阵:

The question is how to enter a matrix like that:

   A =: (something here)
1 3 2 4
7 8 1 2
2 0 0 1
)

之所以问这样一个奇怪的问题，是因为我在某本书中看到了一种类似的使用动词0 : 0或类似方式键入矩阵的方法，但我不记得在哪里. :{

The reason why I'm asking such a weird question is that I have seen in some book a similar method of typing matrices using verb 0 : 0 or something alike, but I cannot remember where. :{

推荐答案

我将(something here)用作(".;._2) 0 : 0.这样，我还可以混合使用表达式.

I use (something here) as (".;._2) 0 : 0. That way I can also mix expressions.

] A =: (".;._2) 0 : 0
5 $ 0
? 5 $ 5
5 $ 1
1 2 3 2 1
)
0 0 0 0 0
2 1 0 0 3
1 1 1 1 1
1 2 3 2 1

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