A basis is a set of vectors that spans a vector space, allowing every vector in that space to be expressed as a linear combination of the basis vectors. Geometrically, basis vectors provide coordinate directions for describing points in high-dimensional spaces. section 2.9 section 2.9.3
A basis has several defining properties:
- Exactly n basis vectors are needed to span an n-dimensional space such as ℝⁿ. section 2.9.3
- Basis vectors need not be orthogonal; any linearly independent pair forms a basis for ℝ². section 2.9.3
- The familiar Cartesian coordinate axes are one basis, but bases are not unique. section 2.9.3
Coordinate directions in ℝ²
The two standard coordinate-direction vectors form a basis for ℝ²: every two-dimensional vector can be represented as a linear combination of them. Replacing them with any two linearly independent vectors gives another basis, even when the directions are not perpendicular. section 2.9.3
