MATLAB Functions | Help Desk |
std
Standard deviation
s = std(X) s = std(X,flag) s = std(X,flag,dim)There are two common textbook definitions for the standard deviation
s
of a data vector X
:s = std(X),
where X
is a vector, returns the standard deviation using (1) above. If X
is a random sample of data from a normal distribution, s2 is the best unbiased estimate of its variance.
If X
is a matrix, std(X)
returns a row vector containing the standard deviation of the elements of each column of X
. If X
is a multidimensional array, std(X)
is the standard deviation of th elements along the first nonsingleton dimension of X
.
s = std(X,flag)
for flag = 0,
is the same as std(X)
. For flag = 1
, std(X,1)
returns the standard deviation using (2) above, producing the second moment of the sample about its mean.
s = std(X,flag,dim)
computes the standard deviations along the dimension of X
specified by scalar dim
.
For matrix X
X = 1 5 9 7 15 22 s = std(X,0,1) s = 4.2426 7.0711 9.1924 s = std(X,0,2) s = 4.000 7.5056
corrcoef
, cov
, mean
, median