I have a matrix

tst=[20 15 26 32 18 28 35 14 26 22 17]

meantst= mean(tst)=23

stdtst= std(tst)=6.6

Matlab command

```
s = std(X)

```

one get standard deviation.

<http://www.mathworks.de/de/help/matlab/ref/std.html>

How can I get std with 1-sigma(68%), 2 sigma(95%), 3sigma(99%)".