Type help cov and note that opt has been removed doesn't exist.
This looks like an Octave bug (at least with version 3.0.5); it works fine in Matlab (at least with version 7.10).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.