I just added these to my sources.list and apt-get update throws this up
Failed to fetch http://anakonda.altervista.org/debian/packages/Packages.gz
302 Found Failed to fetch
http://anakonda.altervista.org/debian/sources/Sources.gz 302 Found Reading
Package Lists... Done
W: Couldn't stat source package list http://anakonda.altervista.org
packages/ Packages
(/var/lib/apt/lists/anakonda.altervista.org_debian_packages_Packages) - stat
(2 No such file or directory)
As instructed on the matplot lib homepage, my sources.list has
deb http://anakonda.altervista.org/debian packages/ deb-src
http://anakonda.altervista.org/debian sources/