Problem with MEANDEV()

[Bruce Axtens]

I'm getting a weird answer from meandev as compared to Excel, Wolfram Alpha and Protium.

GNU Octave, version 3.2.3
Octave was configured for "i686-pc-mingw32"

meandev([8, 8,  9, 11, 11, 15, 16, 19, 19, 20, 20, 21, 21, 25, 32]) --> ans =  5.8571

All the others give 5.46667
e.g. WolframAlpha
http://www.wolframalpha.com/input/?i=mean+deviation%288%2C+8%2C++9%2C+11%2C+11%2C+15%2C+16%2C+19%2C+19%2C+20%2C+20%2C+21%2C+21%2C+25%2C+32%29

What am I doing wrong?

Kind regards,
Bruce.