get a diagonal line in matrix

2 次查看（过去 30 天）
dao
dao 2017-8-21
评论： dao 2017-8-22
Hi, please help me get a diagonal line in matlab. Example, I have a matrix: a = [1 2 3; 4 5 6; 7 8 9] I want to get vector b =[3 5 7] which is a diagonal line of matrix a. This is my code but it doesn't work
a=[1 2 3; 4 5 6; 7 8 9];
b = zeros(1,3);
for i=1:3
for i=1:3
b = a(i,j);
end
end

请先登录，再回答此问题。

采纳的回答

Jan
Jan 2017-8-21
编辑：Jan 2017-8-21
Or:
a = [1 2 3; 4 5 6; 7 8 9];
s = size(a);
index = (numel(a) - s(1) + 1):(1 - s(1)):s(2);
b = a(index)
[EDITED, works with non square matrices now]
  3 个评论
显示 1更早的评论
Jan
Jan 2017-8-22
If you really want a loop:
b = zeros(1,3);
for i = 1:3
b(i) = a(i, 4 - i);
end
dao
dao 2017-8-22
Thank you for your answer, it is neat. in my case, the column and row are equal. How about they are different. Example, I have a matrix 3x4 ? Do I need to use two loop ?

请先登录，再进行评论。

更多回答（1 个）

类别

在 Help Center 和 File Exchange 中查找有关 Creating and Concatenating Matrices 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by