getting error when using diag command

2013 5 5
1 个回答
5 次查看（30 天）

0 个投票

hello i am doing simulation related to duct to control noise and i have structure of matrices, for example i am creating Anr matrices the An and then i want to create Atilta which contains all these matrices according formulas but when i am using diag it gaves me error related to scalar what should i do ?
the formulas are following
*********************
Nmod = 5; % modes in duct 1 to 5
L = 1.2; % length of duct
K = 0.051; % impedance at one end
zi = 0.315;
zm = 0.775;
c = 340 ;
roh = 1.225;
S = 1;
eta =1 ;
betan = -(1:Nmod)*pi/L;
alfa = 1/(2*L)*log((1-K)/(1+K));
Atilta = []; % final matrices
for i = 1:Nmod
%
Anr = c * [alfa betan; -betan alfa]; % formula for Anr matrices
%
Ani = c*eta*[1 0;0 1];
%
An = [Anr -Ani ; Ani Anr]; % Anr and Ani matrices pack in An
Atilta = diag(Atilta,An);
end
***************
from this i want to create state space matrices
and my Atilta matrix will be like this
but when i am using diag command it will give me error as following
Error using diag
K-th diagonal input must be an integer scalar.
Error in modeNmatrices (line 41)
Atilta = diag(Atilta,An);

请先登录，再回答此问题。

回答（1 个）

Walter Roberson
Walter Roberson 2013-5-5

0 个投票

When you use the two-argument form of diag(), the second argument needs to be the number of the diagonal. You cannot use diag() to directly modify an existing array.
I am confused: your error message uses diag() but your code uses blkdiag() which can take an array as its second argument.

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Aniket
Aniket 2013-5-5
no actually i want to use diag but its giving me error so i used blkdiag but its not giving me error but the matrix size is not proper using blkdiag
what should i change in the code to get proper size matrx?
Azzi Abdelmalek
Azzi Abdelmalek 2013-5-5
From your question, you should use blkdiag. What is the expected size of Atila? From your question it should be 20x40
Aniket
Aniket 2013-5-5
yes from my question it is coming 20*40 ,in paper they haven't specified matrix size they just give a matrix structure , its look like in the above diagram
the paper name is
Active Noise Reduction in Ducts of Actuating Dynamics Using Two Periodic Control Signals.
Aniket
Aniket 2013-5-5
Atilta size will depend on number of Nmode ...here i am using Nmod = 5

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Matrices and Arrays 的更多信息

标签

提问:

Aniket
Aniket
2013-5-5

Community Treasure Hunt

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

Start Hunting!

Translated by