Re: A simple question
Norm depens on metric which is given in linear space. If metric is Euclidean (this case has been discussed in messages above) then the norm is counted as the square root of the sum of vector's coordinates in the 2nd power.
However, metric may be city-block, Mahalanobis, etc. Then norm will be expressed in another way.
In general, norm of given vector is the distance between the zero vector and the given vector (norm depends on metrics)
With respect,
Dmitrij