STD Standard Deviation Function

Usage

Computes the standard deviation of an array along a given dimension. The general syntax for its use is

  y = std(x,d)

where x is an n-dimensions array of numerical type. The output is of the same numerical type as the input. The argument d is optional, and denotes the dimension along which to take the variance. The output y is the same size as x, except that it is singular along the mean direction. So, for example, if x is a 3 x 3 x 4 array, and we compute the mean along dimension d=2, then the output is of size 3 x 1 x 4.

Example

The following piece of code demonstrates various uses of the std function

--> A = [5,1,3;3,2,1;0,3,1]
A = 
  <int32>  - size: [3 3]
 
Columns 1 to 3
             5              1              3  
             3              2              1  
             0              3              1

We start by calling std without a dimension argument, in which case it defaults to the first nonsingular dimension (in this case, along the columns or d = 1).

--> std(A)
ans = 
  <double>  - size: [1 3]
 
Columns 1 to 2
    2.516611478423583         1.000000000000000      
 
Columns 3 to 3
    1.154700538379251

Next, we take the variance along the rows.

--> std(A,2)
ans = 
  <double>  - size: [3 1]
 
Columns 1 to 1
    2.000000000000000      
    1.000000000000000      
    1.527525231651947