How to solve error "Arrays have incompatible sizes for this operation?

I'm trying to calculate the standard deviation of noise but when i run my code its giving me an error. I need help please.

this is my code:

L=load("ver.mat");
t_6=(0:numel(L.actual_ver)-0.005);

Ensembl_avg=mean(L.ver);

figure(1);

plot(t_6,Ensembl_avg);
hold on;
plot(t_6,L.actual_ver);
grid on;
xlabel('Time');
ylabel('Ensemble Average and Actual Signal');
title('Ensemble Average and Actual Signal VS Time:');

figure(2);

One_of_the_measurements=50;
plot(t_6,L.ver(One_of_the_measurements,:));
hold on;
plot(t_6,L.actual_ver);
xlabel('Time');
ylabel('Actual Signal and One Measurement');
title('Actual Signal and One Measurement VS Time');

Noise_calc=L.actual_ver-Ensembl_avg;
n=2:100;

for i6=1:length(Noise_calc)
    
    std(Noise_calc(i6));
    std((L.actual_ver-One_of_the_measurements)./sqrt(n));
    
end

Arrays have incompatible sizes for this operation.

[Dyuman Joshi]

load('ver.mat')

size(actual_ver)

ans = 1×2

1 500

n=2:100;
size(n)

ans = 1×2

1 99

You are trying to use element-wise division of 1x500 and 1x99, which is not possible, thus you get the error.

Idk what you are trying to do with that particular operation/line of code, so I can not suggest anything. Please provide additional details as to what your goal is.

Also, you are trying to get the standard deviation of a scalar value, which does not make sense (atleast to me). What is the use of it?

Answer 1

[Mathieu NOE]

hello

I tried to understand what you wanted to do, and so far my suggestion is as follows :

L=load("ver.mat");
t_6=(0:numel(L.actual_ver)-0.005);
Ensembl_avg=mean(L.ver);
figure(1);
plot(t_6,Ensembl_avg);
hold on;
plot(t_6,L.actual_ver);
grid on;
xlabel('Time');
ylabel('Ensemble Average and Actual Signal');
title('Ensemble Average and Actual Signal VS Time:');

figure(2);
One_of_the_measurements=50;
plot(t_6,L.ver(One_of_the_measurements,:));
hold on;
plot(t_6,L.actual_ver);
xlabel('Time');
ylabel('Actual Signal and One Measurement');
title('Actual Signal and One Measurement VS Time');


% std of noise for signal "L.actual_ver" minus "Ensembl_avg"
Noise_calc=L.actual_ver-Ensembl_avg;
std(Noise_calc) % ans =    0.1005

% std of noise for signal "L.actual_ver"  minus "one of the measurements"
% for the 100 measurements (results are stored in S)
for k = 1:100  %( k = one of the measurements);
    S(k) = std((L.actual_ver-L.ver(k,:)));
end
    
figure(3);
plot(S) % shows the std of noise for the 100 measurements (measurement number is the x axis)

[Image Analyst]

If this Answer solves your original question, then could you please click the "Accept this answer" link to award the answerer with "reputation points" for their efforts in helping you? They'd appreciate it. Thanks in advance. 🙂 Note: you can only accept one answer (so pick the best one) but you can click the "Vote" icon for as many Answers as you want. Voting for an answer will also award reputation points.

[Mathieu NOE]

hello again @Gabriela

do you mind accepting my answer (if it has fullfiled your expectations ) ? tx

[Image Analyst]

I accepted it for him. 🙂

[Mathieu NOE]

haha thanks alot @Image Analyst :)