Mean and Norm of a time series.

Question

Haya Ali 2021-5-18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/833148-mean-and-norm-of-a-time-series

编辑： Haya Ali 2021-5-26

I have calculated the mean and norm of a time series. But i am confused because the code gives different values when run in editor and command windows. Please help to resolve the issue

clear all; close all; clc;
x1=[11500.2 11477.9 11417.3 11426.4 11413 11382.9 11375.1 11347.9 11351.1 11329.3]
mx_1 = mean(x1); % assign the computed mean to a variable named mx
for i=1:length(x1)
    x1(i) = (x1(i)-mx_1) / norm(x1); % correct use of norm function and use of variable mx
end
nx_1 = norm(x1); % assign the computed norm to a variable named nx
for i=1:length(x1)
    x1(i) = x1(i)/nx_1; % use of variable nx
end

In editor it gives values as

mx_1 =
   1.1390e+04
   
nx_1 =
    0.0128

but when i write norm (x1) and mean (x1) in command windows it gives this

    norm(x1)
ans =
    1.0000
 mean (x1)
ans =
   -0.0041

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Answer 1

Steven Lord 2021-5-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/833148-mean-and-norm-of-a-time-series#answer_702563

在 MATLAB Online 中打开

The x1 variable you use to calculate mx_1 and nx_1 is not the same x1 that you use in the Command Window.

x1 = 1:10
x1 = 1×10
     1     2     3     4     5     6     7     8     9    10
m1 = mean(x1)
m1 = 5.5000
x1 = normalize(x1, 'zscore') % This changes x1 so
x1 = 1×10
   -1.4863   -1.1560   -0.8257   -0.4954   -0.1651    0.1651    0.4954    0.8257    1.1560    1.4863
m2 = mean(x1) % this variable is not equal to m1
m2 = 0