Definition:Coordinate System/3-Space/Curvilinear
Definition
Recall that we can define Cartesian $3$-space by means of perpendicular planes.
Let us superimpose onto this coordinate system $3$ other one-parameter families of surfaces.
In each of these families, the surfaces need not be parallel and they need not be planes.
These families are such that every point in (ordinary) $3$-dimensional space can then be uniquely identified as the intersection of $3$ such surfaces: one surface from each family.
Hence every point is identified as the ordered triple $\tuple {q_1, q_2, q_3}$, where $q_1$, $q_2$ and $q_3$ are the parameters of each of the families.
Hence we can describe a curvilinear coordinate system.
Curvilinear Coordinate Surface
Let $\KK$ be a curvilinear coordinate system in $3$-space.
Let $\QQ_1$, $\QQ_2$ and $\QQ_3$ denote the one-parameter families that define $\KK$.
Each of the surfaces which is an element of $\QQ_i$ is known as a curvilinear coordinate surface.
Each curvilinear coordinate surface has its unique $q_i$ which is constant for that surface.
Sources
- 1970: George Arfken: Mathematical Methods for Physicists (2nd ed.) ... (previous) ... (next): Chapter $2$ Coordinate Systems $2.1$ Curvilinear Coordinates