How to plot y = Cexpm(At)*B?

Question

Ljix 2016-2-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/266458-how-to-plot-y-c-expm-a-t-b

评论： Star Strider 2016-2-5

How to plot y = C*expm(A*t)*B, where A,B and C are matrices? I tried defining t=linspace(0,100,25) and then calculate y as function (as defined) and I got message about dimension error.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Star Strider 2016-2-3

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/266458-how-to-plot-y-c-expm-a-t-b#answer_208413

在 MATLAB Online 中打开

This works:

A = [1 -4; 3 -5];                                   % Define System Matrices
B = [1; 1];
C = [1 0; 0 1];
N = 50;                                             % Length Of Simulation (Samples)
t = linspace(0, 5, N);                              % Time Vector
u = ones(2, N);                                     % System Input
for k1 = 1:length(t);
    y(:,k1) = C*expm(A*t(k1))*B.*u(:,k1);           % Evaluate System At Each Time & Input
end
figure(1)
plot(t, y)
grid

3 个评论
显示 1更早的评论隐藏 1更早的评论

Star Strider 2016-2-3

The dot is an operator that converts the matrix multiplication operator (*) to an element-wise operator (.*). See the documentation for Array vs. Matrix Operations for a fun and interesting time!

Star Strider 2016-2-5

The (1x2) vector for ‘C’ should work, because the other matrices are (2x2). It would then produce a column-vector output.

The problem is with ‘u=ones(1,N)’. The ‘u’ vector has to have two rows at any time (or equivalently, index) to work in my example, although they do not have to be all 1. The ‘u’ is the input to the dynamical system, so it can have any value, providing that every column presented to the system as an input has two rows. That is likely where the dimension error originates.

请先登录，再进行评论。