# For loop error: Subscript indices must either be real positive integers or logicals

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Mohsina Zafar on 12 Jul 2019
Commented: Mohsina Zafar on 12 Jul 2019
I am executing a for loop but it gives following error at time 0.6:
T_o=[0;0;0];
T_d=[0;0;0];
T_l=[0;0;0];
out_n=zeros([],3);
for t=0:0.1:10
T_o = [0.05*(10-t);0.04*(10-t);0.03*(10-t)];
T_e=T_d-T_o;
T_e=[t*10 T_e'];
a = sim('PD_control','SimulationMode','normal');
out = a.get('T_u');
out_n(t*10+1,:) = out(2,:)
end
The Simulink file called by this code is attached here.

KSSV on 12 Jul 2019
T_o=[0;0;0];
T_d=[0;0;0];
T_l=[0;0;0];
out_n=zeros([],3);
tt=0:0.1:10 ;
for i = 1:length(tt)
t = tt(i) ;
T_o = [0.05*(10-t);0.04*(10-t);0.03*(10-t)];
T_e=T_d-T_o;
T_e=[t*10 T_e'];
a = sim('PD_control','SimulationMode','normal');
out = a.get('T_u');
out_n(i,:) = out(2,:)
end

#### 1 Comment

Mohsina Zafar on 12 Jul 2019
Great! Exactly what I needed.

### More Answers (1)

Walter Roberson on 12 Jul 2019
mat2str((find((0:0.1:10)*10-(0:100))-1)/10)
0.3 0.6 0.7 1.2 1.4 2.3 2.4 2.8 2.9 4.1 4.6 4.8 5.2 5.4 5.9 6.2
That is, 0.3 * 10 is not 3.0 exactly.
0.1 in binary floating point is not exactly 1/10, just the same way that in decimal 0.333...3 * 3 is 0.999...9 instead of 1

#### 1 Comment

Mohsina Zafar on 12 Jul 2019
Thanks. Didn't know this before.