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by extasia 648 days ago
That’s not mathematically accurate though, is it? We haven’t reduced the dimension of the vector by one.

Pray tell, which dimension do we lose when we normalize, say a 2D vector?

3 comments

Mathematically, it's fine to say that you've lost the magnitude dimension.

Before normalization, the vector lies in R^n, which is an n-dimensional manifold.

After normalization, the vector lies in the unit sphere in R^n, which is an (n-1)-dimensional manifold.

Magnitude, obviously.

>>> Magnitude is not a dimension [...] To prove this normalize any vector and then try to de-normalize it again.

Say you have the vector (18, -5) in a normal Euclidean x, y plane.

Now project that vector onto the y-axis.

Now try to un-project it again.

What do you think you just proved?

A circle circumference is a line, is 1D?