MATLAB Answers

dimension error with * operator

11 ビュー (過去 30 日間)
Douglas Brenner
Douglas Brenner 2018 年 9 月 28 日
コメント済み: OCDER 2018 年 9 月 28 日
This line of code: asynch = C1(:)*N(:)*C(:)'/(delta-2) throws an error: Error using * Inner matrix dimensions must agree. That would seem to be right C1 is a 1X100 double and N is a 100x100 double. So I changed the code to T = transpose(C1); asynch = C1(:)*N(:)*T(:)'/(delta-2). This makes T a 100X1 double and the code should run but I get the same error. What's wrong. Thanks

  1 件のコメント

OCDER
OCDER 2018 年 9 月 28 日
synch = C1(:)*C1(:)'/(delta-2)
^
This works because of the transpose operator.
C1(:) = Nx1 vector
C1(:)' = 1xN vector
so C1(:)*C1(:)' works as a (Mx1) * (1xM) = MxM vector (inner dimension agrees)
In your case, you have a matrix N that is 100x100.
N = 100x100 matrix
N(:) = 10000x1 vector
C(:)*N(:) will NOT WORK because it's a (Mx1) * (10000x1) = ????

サインインしてコメントする。

回答 (3 件)

OCDER
OCDER 2018 年 9 月 28 日
Although N is a 100x100 matrix, when you do N(:), you make it into a 10000x1 vector. Get rid of the "(:)" when you want to proper matrix math.

  0 件のコメント

サインインしてコメントする。


Pratik Bajaria
Pratik Bajaria 2018 年 9 月 28 日
Hello,
Try .* operator. It is the normal matrix multiplication, the one you are trying is doing a Hadamard multiplication.
Regards, Pratik

  0 件のコメント

サインインしてコメントする。


Douglas Brenner
Douglas Brenner 2018 年 9 月 28 日
The paper from which I got the code uses * and that works in this line: synch = C1(:)*C1(:)'/(delta-2). Not only do I not get an error but I get what I think is the right answer. For asynch = C1(:)*N(:)*C(:)'/(delta-2), I think the problem is that N is 2D and C1 is one D but I got that code from the paper too.

  0 件のコメント

サインインしてコメントする。

製品


リリース

R2014a

Community Treasure Hunt

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

Start Hunting!

Translated by