Physlib.SpaceAndTime.Space.Origin
The origin of `Space` and the Euclidean chart
The choice of origin for `Space d` is its vector-space zero `(0 : Space d)`. This file provides that `Zero` instance and the standard chart, isolated so they can be shared by the full module structure (`Space/Module.lean`) and the Euclidean action (`Space/EuclideanGroup/Action.lean`) without those depending on each other.
* `(0 : Space d)` — the coordinate origin, the point all of whose coordinates vanish. * `Space.chartEuclidean` — the standard affine isometry `Space d ≃ᵃⁱ[ℝ] EuclideanSpace ℝ (Fin d)`, `p ↦ p -ᵥ 0`, identifying a point with its coordinate vector relative to the origin.
5 declarations
Map from to via the origin
For a given dimension , this function maps a vector from the -dimensional Euclidean vector space (specifically `EuclideanSpace ℝ (Fin d)`) to a point in the affine space . The resulting point is obtained by translating the origin by the vector , denoted mathematically as .
The -th coordinate of equals
For any dimension , vector , and index , the -th coordinate of the point in is equal to the -th component of the vector .
For any dimension and any vector (represented by `EuclideanSpace ℝ (Fin d)`), the displacement vector from the origin to the point is equal to . That is, .
Standard Euclidean chart via
For any dimension , the standard Euclidean chart is an affine isometry equivalence between the -dimensional flat Euclidean space and the Euclidean vector space . It identifies each point with its coordinate vector relative to the origin via the displacement map:
For any dimension and any point in the -dimensional flat Euclidean space , the value of the standard Euclidean chart at is equal to the displacement vector from the origin to : where denotes the origin in and denotes the displacement vector operation (subtraction in the affine space).
