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

Question

Gabriela 2023-9-15

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2021676-how-to-solve-error-arrays-have-incompatible-sizes-for-this-operation

评论： Mathieu NOE 2023-12-12

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.

1 个评论
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Dyuman Joshi 2023-9-15

在 MATLAB Online 中打开

ver.mat

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?

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Answer 1

Mathieu NOE 2023-9-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2021676-how-to-solve-error-arrays-have-incompatible-sizes-for-this-operation#answer_1312482

在 MATLAB Online 中打开

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)