The percentile
function was added in version 1.5.x. You will need to upgrade to at least that version.
Did you try:
sudo pip install numpy==1.7.1 --upgrade
To check which version you are running, start the python console and run:
>>> import numpy
>>> print numpy.__version__
You can also do:
sudo pip freeze | grep numpy
The Ubuntu 9.10 numpy package uses version 1.3.03. It is likely that installing version 1.7.0 vai pip was successful, but your machine is defaulting to the python-numpy version instead. You can remove by running:
sudo apt-get remove python-numpy