On: How does cosine similarity work?

[extasia]

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?

[creata → extasia]

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.

[thaumasiotes → extasia]

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?

[langcss → extasia]

A circle circumference is a line, is 1D?