Error using plot Vectors must be the same length.

clear, clc, close all
DataStruct_IMU = importdata("IMU_Data.tsv");
Time_IMU = DataStruct_IMU.data(:,1);
Omega_IMU = DataStruct_IMU.data(:,2);
h = mean(diff(Time_IMU));
n = length(Omega_IMU);
Aplha_IMU(1)=(-3*Omega_IMU(1) + 4*Omega_IMU(2) - Omega_IMU(3))/(2*h);
for i = 2:n-1
    Alpha_IMU(i) = (Omega_IMU(i+1)-Omega_IMU(i-1))/(2*h);
end
Aplha_IMU(n) = (Omega_IMU(n-2)-4*Omega_IMU(n-2) + 3*Omega_IMU(n))/(2*h);
figure('units','normalized','outerposition',[0 0 1 1])
title({'CVEN 308 Module 3','Numerical integration and differentiation of pendulum motion'})
subplot(1,1,1)
hold on
plot(Time_IMU,Alpha_IMU,'b')

I got following error

Error using plot

Vectors must be the same length.

Error in Copy_2_of_Data_Analysis_Starter (line 23)

plot(Time_IMU,Alpha_IMU,'b')

[the cyclist]

Can you upload the data file? (You can use the paper clip icon in the INSERT section of the toolbar.) That will make things much easier to debug.

[NANDEESWARAN]

clear, clc, close all
DataStruct_Vid = importdata("Video_Data.tsv");

Error using importdata
Unable to open file.

Time_Vid = DataStruct_Vid.data(:,1);
Theta_Vid = DataStruct_Vid.data(:,2);
DataStruct_IMU = importdata("IMU_Data.tsv");
Time_IMU = DataStruct_IMU.data(:,1);
Omega_IMU = DataStruct_IMU.data(:,2);
h = mean(diff(Time_IMU));
n = length(Omega_IMU);
Aplha_IMU(1)=(-3*Omega_IMU(1) + 4*Omega_IMU(2) - Omega_IMU(3))/(2*h);
for i = 2:n-1
    Alpha_IMU(i) = (Omega_IMU(i+1)-Omega_IMU(i-1))/(2*h);
end
Aplha_IMU(n) = (Omega_IMU(n-2)-4*Omega_IMU(n-2) + 3*Omega_IMU(n))/(2*h);
figure('units','normalized','outerposition',[0 0 1 1])
subplot(1,1,1)
hold on
plot(Time_IMU,numel(Alpha_IMU)-1,'b')

I Cannot able to create graph I dunno where I making mistake.

Thanks

[Voss]

Change "Aplha_IMU" to "Alpha_IMU" in the two places I mentioned in my answer.

[NANDEESWARAN]

Thanks you so much.

[Voss]

You're welcome! So is the problem solved now?

Answer 1

[Voss]

You assign to

Aplha_IMU(n)

but it should be

Alpha_IMU(n)

(Similarly for Aplha_IMU(1), but that's not the cause of the error.)

[NANDEESWARAN]

Thanks

[Voss]

You're welcome! Any questions, let me know. Otherwise, please Accept this answer. Thanks!

[Voss]

@NANDEESWARAN: Did this fix the problem?

[Voss]

An explanation: Those typos have the effect of creating two vectors: Aplha_IMU (the erroneous one), which is of length n, and Alpha_IMU (the one you wanted to plot with), which is of length n-1 (because its nth element never gets assigned).

See below:

n = 5;

Aplha_IMU(1) = 1;
for i = 2:n-1
    Alpha_IMU(i) = i;
end
Aplha_IMU(n) = n;

% the one you wanted to create has n-1 elements.
% notice its first element is zero becuase it was never explicitly
% assigned.
Alpha_IMU

Alpha_IMU = 1×4

0 2 3 4

% the erroneously created vector has n elements.
% but it's all zeros except for the first and last element because only its
% first and last elements were explicitly assigned.
Aplha_IMU

Aplha_IMU = 1×5

1 0 0 0 5

So then when you try to plot Alpha_IMU against Time_IMU, you get the error you got because Alpha_IMU has n-1 elements while Time_IMU has n elements.