error while running a loop inside transfer function

Question

Kobi 2013-4-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/72647-error-while-running-a-loop-inside-transfer-function

i'm trying to change the value of k from to 0.1:0.1:7 and when i try this i get this error

??? Error using ==> InputOutputModel.subsasgn at 58
Subscript indices must either be real positive integers or logicals.
Error in ==> spect at 7
G(k)=tf([k],[10*10^-3 1]);

my code:

for k=0.1:0.1:7;
G(k)=tf([k],[10*10^-3 1]);
end

how can i fix that?

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Answer 1

Walter Roberson 2013-4-18

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https://ww2.mathworks.cn/matlabcentral/answers/72647-error-while-running-a-loop-inside-transfer-function#answer_82750

在 MATLAB Online 中打开

You are trying to assign the value of the tf() call into G(k) when k is not an integer. Subscripts must be positive integers.

kvals = 0.1 : 0.1 : 7;
for kidx = 1 : length(kvals)
  k = kvals(kidx);
  G(kidx) = tf([k],[10*10^-3 1]);
end

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Kobi 2013-4-19

在 MATLAB Online 中打开

ok, but i still don't fully understand what this line does:

k = kvals(kidx);

i'm trying to do the same for all of my program like that:

kvals=0.1:0.1:7; % Change the values of k parameter
for kidx=1:length(kvals);
    k=kvals(kidx);
G(kidx)=tf([k],[10*10^-3 1]);
Gtotal(kidx)=feedback(G(k),1);
TAU(kidx)=(G(k).den{1}(1))/(G(k).num{1}(2));
end

and i get this error

??? Error using ==> InputOutputModel.subsref at 44
Subscript no. 2 is out of range.
Error in ==> Untitled at 5
Gtotal(kidx)=feedback(G(k),1);

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Answer 2

Kobi 2013-4-20

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/72647-error-while-running-a-loop-inside-transfer-function#answer_82942

在 MATLAB Online 中打开

please help i don't understand what am i doing wrong

clear all
clc
kvals=0.1:0.1:7; % Change the values of k parameter
for kidx=1:length(kvals);
k=kvals(kidx);
G(kidx)=tf([k],[10*10^-3 1]);
Gtotal(kidx)=feedback(G(k),1);
TAU(kidx)=(0.01)/(G(k).num{1,1}(2));
end