[@$3.1415rin]

I didnt knew if I should add this matrix stuff, but since there are some function in HL2 ( I guess there wasnt any in HL1 ) using matrices, I thought it might be handy to have a little simple paragraph about them.

About different methods of determining the length of the vector : well, that's the general way to write that down. You are _not_ always using euclidian distances, e.g. most of us are using some sort of manhattan distance in their A* implementations. so it's not that far off, maybe shouldnt have written the general formula of that.

and ok, einstein convention might be a bit misplaced here, especially when nobody reads a book about related stuff. it's anyway widely used.

about more code : from my point of view I better like a simple formula than some piece of code, which might already include optimizations, component wise calculating, etc. which don't make the point of topic more obvious. especially code with unneccessary stuff like "pBot->" crap. that has nothing to do with the algorithm, so why put it there ?
just saw your comment : ok, that might be a reason, another reason is that your code would be easier just to copy and paste without understanding for all those using podbot or close to hpb bot code. if you understand it, there is no question of what you want to save and what not, otherwise, you are fucked anyway.

PS: and if you like greek characters or not ... well, that's just personal taste, isnt it ? i'm often writing scalar coefficients as greek characters, as well as transformations.