Returns the standard deviation of the all entries of the specified matrix. The standard deviation of a set of N numbers X = [x 1 ,...,x N ] is defined as
$$ \sigma=\sqrt{\frac{1}{N} \sum_{i=1}^{N}\left(x_{i}-\mu\right)^{2}} $$
where μ is the mean of X.
Syntax |
Description |
---|---|
out = std(A); |
Will return the standard deviation of matrix A, over all dimensions. |
Example
These are some simple examples showing how to use this command.
a =[1,2,3,4,5]; ?std(a); result: 1.41421 b =[1,2,3,4,5;5,4,3,2,1;1,4,2,5,8]; ?std(b); ?sqrt(sum((b-mean(b))^2)/length(b)); # Compare with equivalent calculation using sum and mean result: 1.88562 result: 1.88562 d = randmatrix(3,3,3); ?d; result(i,j,1): 0.345988 0.84698 0.271889 0.471725 0.316874 0.982971 0.374981 0.456099 0.2978 result(i,j,2): 0.739189 0.761315 0.5009 0.567278 0.839442 0.890164 0.19599 0.397656 0.0274667 result(i,j,3): 0.994629 0.531327 0.626759 0.572588 0.194067 0.657613 0.0505081 0.843043 0.197851 ?std(d); result: 0.274514
See Also