# Array indices must be positive integers or logical values. Error in (line 8) mr(t)=mi-(​(mi-mf)*(t​./tb));

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Chukwunememma Uponi on 29 Nov 2019
Answered: Image Analyst on 29 Nov 2019
mi=2290000
mf=130000
tb=165
t= linspace(6.5,165,1);
mr(t)=mi-((mi-mf)*(t./tb));
mr=[]
for t=6.5:165;
mr(t)=mi-((mi-mf)*(t./tb));
end
I have no idea what's wrong with the for loop, and I don't see an error in line 8. Any help please?

Stephan on 29 Nov 2019
Edited: Stephan on 29 Nov 2019
I doubt you want t to have only one point. Also no for loop is needed:
mi=2290000;
mf=130000;
tb=165;
t=linspace(6.5,165);
mr=mi-((mi-mf)*(t/tb));
plot(t,mr)

#### 1 Comment

Chukwunememma Uponi on 29 Nov 2019
thank you!

Rafael Hernandez-Walls on 29 Nov 2019
Hi,
Yo have 2 errors. First you have the line when you define the vector time:
t=linspace(6.5,164,1) % You need to put the number of points (you have only one point)
You dont need to put mr(t), because t isnt integer and you need a integer (is a index of the vector). you need to put only this line
mr=mi-((mi-mf)*(t./tb));
You dont need the loop for
Rafael

#### 1 Comment

Chukwunememma Uponi on 29 Nov 2019
thank you!

Image Analyst on 29 Nov 2019
You can't have the 6.5th element of an array. You can have the 6th or 7th but not the 6.5th. Your question is a FAQ, so read the FAQ on it, plus on several other common errors and other fascinating things.