Adding each row to previous row in a vector-Not Cumulative

7 次查看（过去 30 天）
Hajik zagori
Hajik zagori 2011-7-20
Hi , I've looked everywhere to find the solution for this but I couldn't find the answer. Here 's the problem. How to add each row in a vector with just the previous row? For example here is the process on this vector: A=[2 1 7 9 4] and the answer should be this vector: C=[3 8 16 13]
Thanks in advance.

请先登录，再回答此问题。

采纳的回答

Sukuchha
Sukuchha 2011-7-20
A=[2 1 7 9 4]; B = A(1:end-1)+diff(cumsum(A));
  1 个评论
Jan
Jan 2011-7-20
diff(cumsum(A)) ?! An expensive method to get: A(2:end). But in addition there is the danger of rounding errors, e.g. diff(cumsum([1e16, 1, 5])) is [0, 4] ! Therefore I strongly recommend not to use this.

请先登录，再进行评论。

更多回答（3 个）

Jan
Jan 2011-7-20
Easier and faster:
B = A(1:end-1) + A(2:end)
  2 个评论
Sukuchha
Sukuchha 2011-7-21
Jan, your method is better ! i feel like stupid now ! I need to remember always solve problems in a simplier way !
Jan
Jan 2011-7-21
@Sukuchha: Often a direct translation of the human language is helpful. You've formulated your algorithm very clear already: "add each row in a vector with just the previous row". So you did solve the biggest part of the problem already. Most of the questions in this forum are much less clear.

请先登录，再进行评论。

Paulo Silva
Paulo Silva 2011-7-20
C=arrayfun(@(x)plus(A(x),A(x-1)),2:numel(A))
or with a for loop
C=zeros(1,size(A,2)-1);
for x=2:size(A,2)
C(x-1)=A(x)+A(x-1);
end
C
Hajik zagori
Hajik zagori 2011-7-20
I used Sukuchha method and it worked.Thanks Sukuchha. But I should also thank Paulo Silva.

类别

在 Help Center 和 File Exchange 中查找有关 Logical 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