Calculating the Standard Deviation

3 次查看(过去 30 天)
Hi,
How to read each value from a txt file for calculation of standar deviation (SD).
For example, I have my txt file with Y values (frequencies) and I want to caulate how much of variation from the mean the frequencies change. I can do it manually but for many data this would be too slow process. So, I want to automatically read and calculate the SD.
My file has jus one colum. To calculate the SD I have to calculate mean first, so would be: Mean = A/n
The variable A would be the sum of each value in my file divivded by the total number of values. Attached is the file. Then, I can calculate the SD which is
the sqr((A(1)-Mean)^2 + (A(2)-Mean)^2 + ... + (A(N)-Mean)^2/n-1).
Is there a way to do it automatic?
Thank you

采纳的回答

Star Strider
Star Strider 2021-5-5
Two options are to either calculate it directly, or use the normalize funciton —
y = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/608245/y%20axis.txt')
y = 400×1
10.5400 10.5200 10.5231 10.5138 10.5015 10.5015 10.5108 10.5046 10.5231 10.4846
ymean = mean(y)
ymean = 10.2223
stdvct = sqrt((y-ymean).^2)
stdvct = 400×1
0.3177 0.2977 0.3008 0.2916 0.2792 0.2792 0.2885 0.2823 0.3008 0.2623
[N,C,S] = normalize(y,'center','mean')
N = 400×1
0.3177 0.2977 0.3008 0.2916 0.2792 0.2792 0.2885 0.2823 0.3008 0.2623
C = 10.2223
S = 1
  5 个评论
Tay
Tay 2021-5-19
Thank you.
I calculated directed using the equation more easy than tryng to find the error xD

请先登录,再进行评论。

更多回答(0 个)

类别

Help CenterFile Exchange 中查找有关 Loops and Conditional Statements 的更多信息

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by