Matrix multiplication along a specified dimension?

18 ビュー (過去 30 日間)
Darcy Cordell
Darcy Cordell 2022 年 9 月 28 日
コメント済み: James Tursa 2022 年 9 月 28 日
I have a 2x2xN matrix, A, and a 2xN matrix, X. I want to multiply each Nth 2x2 matrix in A by the Nth 2x1 matrix in X. I can do this with:
for i = 1:N
B(:,i) = A(:,:,i)*X(:,i);
end
However, this is very slow, especially in my case where N is large.
Is there a way to do matrix multiplication "along a specified dimension" without a for loop?
Apologies if this is a duplicate question, I looked and could not find anything. Most of the other answers I found involve element-wise multiplication along a specified dimension, which is different than what I am doing.

採用された回答

Matt J
Matt J 2022 年 9 月 28 日
B=pagemtimes(A,X)
  2 件のコメント
Darcy Cordell
Darcy Cordell 2022 年 9 月 28 日
Exactly what I was looking for! The speed up is impressive. I would just add that in order for this to work, it is necessary to permute X to be 2x1xN using permute(X,[1,3,2]). Thanks!
James Tursa
James Tursa 2022 年 9 月 28 日
Or reshape(X,2,1,[]);

サインインしてコメントする。

その他の回答 (0 件)

カテゴリ

Help Center および File ExchangeResizing and Reshaping Matrices についてさらに検索

Community Treasure Hunt

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

Start Hunting!

Translated by