Why do i get the error: Array indices must be positive integers or logical values?

Hi, ive been trying to plot 3 sets of data on the same graph plot and i keep getting this error message :Array indices must be positive integers or logical values in my for loop

[Stephen23]

Original question by Sebastion Sunny retrieved from Google Cache:

https://webcache.googleusercontent.com/search?q=cache:Vdd4G_jnqhUJ:https://www.mathworks.com/matlabcentral/answers/1603540-why-do-i-get-the-error-array-indices-must-be-positive-integers-or-logical-values

https://web.archive.org/web/20211210124526/https://www.mathworks.com/matlabcentral/answers/1603540-why-do-i-get-the-error-array-indices-must-be-positive-integers-or-logical-values

Why do i get the error: Array indices must be positive integers or logical values?

Hi, ive been trying to plot 3 sets of data on the same graph plot and i keep getting this error message :Array indices must be positive integers or logical values in my for loop

WindSpeeds = linspace(0,30,300);%m/s
deltaT = 0.01;
time = 0:deltaT:300;
%preallocation
rotorTorque = zeros(length(WindSpeeds),1); %Nm
turbinePower = zeros(length(WindSpeeds),1);
generatorTorque = zeros(length(WindSpeeds),1);
omegaRotor = zeros(length(WindSpeeds),1);
%eulers method
for i = 2:length(time)
    omegaRotor(i) = omegaRotor(i-1) + deltaT((windTurbineRotorModel(WindSpeeds,Ct,D,Vcutout,Vrated,Vcutin))-(k*omegaRotor(i-1).^2)/j);
end

this is the code ive written at the moment

Thank you

Answer 1

[Voss]

This expression in the loop:

deltaT((windTurbineRotorModel(WindSpeeds,Ct,D,Vcutout,Vrated,Vcutin))-(k*omegaRotor(i-1).^2)/j)

says to get the elements of deltaT with index (or indices) equal to the value of:

(windTurbineRotorModel(WindSpeeds,Ct,D,Vcutout,Vrated,Vcutin))-(k*omegaRotor(i-1).^2)/j

I don't know what the value of that expression is because most of those variables are undefined, but given that deltaT is a scalar variable, I would guess that indexing it like that is not what you mean to be doing.

[Sebastian Sunny]

Forgot the multiplication sign thank you