Standard Deviation
The standard deviation is the square root of variance:
The built-in function in a MATLAB for the standard deviation is known as std; the standard deviation can be found either as the sqrt of the variance, or by using std:
>> shortx = [2 5 1 4];
>> myvar = var(shortx)
myvar =
3.3333
>> sqrt(myvar)
ans =
1.8257
>> std(shortx)