how to calculate standard deviation of 1D array?

i have an array A.

A=[1 2 3 4];
s=std(A);

Error: Index exceeds matrix dimensions.

• sometimes std says: Subscript indices must either be real positive integers or logicals.
• and also what is the difference in std and std2.

Answer 1

[Star Strider]

1. You most likely have a variable named std. This command should give you that information (copy-paste it to the Command Window and run it):

which std -all

If you have a Windows computer, all those results should be in the C:\Program Files\MATLAB\... directories, and none in your user files or as variables.

2. The std function takes the standard deviation across the columns (or rows) of an array, producing one value for each column (or row). The std2 function takes the standard deviation of all the elements in the array, as though they were all a single vector.

[Ayush]

Thanks.. Got it working. Std was used somewhere. Restarting matlab, solved the problem.

[Star Strider]

My pleasure!

(The most sincere expression of appreciation here on MATLAB Answers is to Accept the Answer that most closely solves your problem.)

Answer 2

[John D'Errico]

How? Use std to compute a standard deviation. Read the help.

DON'T NAME YOUR VARIABLE STD. If you do, you will get that error message!

As far as the difference between std and std2, MATLAB does not have a std2 function in it. Maybe somebody you know has written a std2 code. I can't guess.

[Star Strider]

The std2 function is in the Image Processing Toolbox.

Answer 3

[Ayush]

Thanks.. Got it working. Std was used somewhere. Restarting matlab, solved the problem.

Answer 4

[Ken Irok]

Hi, I have a 74 row of array stored in my workplace called "feat". How do I calculate the std and mean for each column in that array? Say there is 6 different columns inside that array of workplace.

[Star Strider]

Read the documentation for std and mean.