BIZNIQUE / LINEAR ALGEBRA / 17
See perpendicular vectors through a dot product
See perpendicular vectors through a dot product
Rotate a direction and watch its component along another direction disappear.
BIZNIQUE / LINEAR ALGEBRA / 17
Rotate a direction and watch its component along another direction disappear.
THE IDEA
Two nonzero vectors are orthogonal when their dot product is zero. Projection onto a unit direction v uses the scalar xᵀv. Orthogonal components let us separate contributions without counting the same direction twice.
uᵀv = ‖u‖₂‖v‖₂ cos θ
Uncorrelated random variables and geometrically orthogonal vectors are related through centred data, but neither automatically means statistical independence.
TRY IT YOURSELF
What is the dot product of (1, 2) and (2, −1)?
1×2 + 2×(−1) = 0, so the vectors are orthogonal.