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?

Answer 1

[Walter Roberson]

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

[Kobi]

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);

Answer 2

[Kobi]

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

this thing just won't work.