# how can i compute the stander diviation and confidence intervales for a matrix?

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Commented: the cyclist on 18 Jan 2022
i have matrix 51 rows and71 columns and i would like to compute and plot the result of std also i need to compute the confidence intervals 95%?
also after computing the std can i use imagesc command in order to see the range of std for the matrix ?
thank you

the cyclist on 15 Jan 2022
If you have the Image Processing Toolbox, you can use the std2 function to compute the standard deviation of all the elements of a matrix. If not, you can use std from base MATLAB, but you need to make a vector out of the matrix first.
A = magic(5);
std2(A)
ans = 7.3598
std((A(:)))
ans = 7.3598
Sorry, but I didn't really understand your second question.
the cyclist on 18 Jan 2022
N = 1000;
X1 = randn(N,1);
X2 = randn(N,1) + 100;
X = [X1, X2];
x_lower = prctile(X, 2.5)
x_lower = 1×2
-1.9542 97.9812
x_upper = prctile(X,97.5)
x_upper = 1×2
1.9782 101.7530
Here I have defined two vectors (of equal length), put them into a matrix, and calculated the confidence interval for both vectors simultaneously.