Some notation

Vectors are usually given a name just like variables and then are written with an arrow over the name, such as to distinguish it from the scalar variable w which only holds one piece of information. If a vector ``lives'' in an n-dimensional world (in other words, it is a list of n different real numbers) then we write `` '' to let us know that

1. is a vector,
2. contains n different pieces of information, and
3. each of the n pieces of information is a sinlge real number.

Vectors can live in spaces other than , but usually this space will be good enough for us, especially since vectors in this space have a very nice graphical interpretation.