How I compute multiple sum in matlab for 4D matrix?

4 次查看（过去 30 天）
Mehdi
Mehdi 2018-9-11
评论： Mehdi 2018-9-11
How I compute multiple sum in matlab for 4D matrices as below? U and V are 4D matrices.
  12 个评论
显示 10更早的评论
Mehdi
Mehdi 2018-9-11
编辑：Mehdi 2018-9-11
As I said I have many similar expressions like that and it seems your method is not applicable for more expressions. I am searching a similar command like add in Maple.
Matt J
Matt J 2018-9-11
编辑：Matt J 2018-9-11
If they are "similar", my method - which is to use the sum command - is applicable. Have you read the documentation on sum()? It is the best analogue of add that you will find in Matlab.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Matt J
Matt J 2018-9-11
编辑：Matt J 2018-9-11
Notice that the only indices shared between U and V are j and q. Therefore, you can minimize multiplication operations as follows,
partialU=sum(sum(U,4),1); %sum over i and r
partialV=sum(sum(V,4),1); %sum over k and s
A=sum(partialU(:).*partialV(:)); %sum over j and q
  6 个评论
显示 4更早的评论
Matt J
Matt J 2018-9-11
编辑：Matt J 2018-9-11
You should edit your original post with this new equation and information about q_r and q_s. The new expression is rather unclear. You have the symbol q being used for two different things, both as a symbolic variable and as an index of summation.
Mehdi
Mehdi 2018-9-11
I asked the question in new page as below: https://uk.mathworks.com/matlabcentral/answers/418526-what-is-the-best-way-to-calculate-multiple-summations-expression-in-matlab

请先登录，再进行评论。

类别

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

标签

产品


版本

R2018a

Community Treasure Hunt

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

Start Hunting!

Translated by