Index in position 2 exceeds array bounds (must not exceed 1).

Question

Jamie Jenkinson 2021-4-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/805136-index-in-position-2-exceeds-array-bounds-must-not-exceed-1

评论： Jamie Jenkinson 2021-4-17

采纳的回答： David Fletcher

clc

A= [ -0.0240 -9.5113 0 -0.2973

0.0010 -1.1746 0 1.1758

0 2.3532 -0.9461 -2.3532

0 0 1.0000 0];

B = [0.8 0; 0 0; 0 -2.39; 0 0];

C = [1 0 0 0];

D = [0 0];

sys_1=ss(A,B,C,D);

[n1,d1]=ss2tf(A,B,C,D,2);

time = 0:0.005:10;

figure(1);

y_v=step(sys_1,time);

V_Plot=plot(time,y_v(:,2,1),'LineWidth',2);

ylabel('(m/s)');

xlabel('(s)');

title('V');

grid on;

Index in position 2 exceeds array bounds (must not exceed 1).

Error in SS2TF (line 14)

V_Plot=plot(time,y_v(:,2,1),'LineWidth',2);

Im trying to run this code. Im looking to extract data from the four columns of matrix A, and the 2 columns of matrix B. I thought this was done using the (:,:,:) after the step of the plot but I keep getting an error saying ive exceeded array bounds. I thought there was a way I can get the (muse not exceed) to 4, and 2 if that makes sense. However it wont let me exceed 1 for both. Any help is appreciated

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Clayton Gotberg 2021-4-17

What size is y_v? MATLAB's step command should only return one state at a time with the inputs you've supplied here.

If you want multple states, change the output matrix C from [1 0 0 0] (outputting only the first state) to something like [1 0 0 0; 0 1 0 0] (outputting the first and second states).

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Answer 1

David Fletcher 2021-4-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/805136-index-in-position-2-exceeds-array-bounds-must-not-exceed-1#answer_677811

编辑：David Fletcher 2021-4-17

在 MATLAB Online 中打开

y_v is 2001x1x2 - you are trying to index the second column which does not exist. Do you mean this?

clc
A=   [   -0.0240   -9.5113         0   -0.2973
          0.0010   -1.1746         0    1.1758
               0    2.3532   -0.9461   -2.3532
               0         0    1.0000         0];
B = [0.8 0; 0 0; 0 -2.39; 0 0];
C = [1 0 0 0];
D = [0 0];
sys_1=ss(A,B,C,D);
[n1,d1]=ss2tf(A,B,C,D,2);
time = 0:0.005:10;
figure(1);
y_v=step(sys_1,time);
V_Plot=plot(time,y_v(:,1,2),'LineWidth',2);
ylabel('(m/s)');
xlabel('(s)');
title('V');
grid on;