# Definition:Contour/Image

## Definition

Let $\R^n$ be a real cartesian space of $n$ dimensions.

Let $C$ be a contour in $\R^n$ defined by the (finite) sequence $\sequence {C_1, \ldots, C_n}$ of directed smooth curves in $\R^n$.

Let $C_i$ be parameterized by the smooth path $\rho_i: \closedint {a_i} {b_i} \to \R^n$ for all $i \in \set {1, \ldots, n}$.

The image of $C$ is defined as:

$\ds \Img C := \bigcup_{i \mathop = 1}^n \Img {\rho_i}$

where $\Img {\rho_i}$ denotes the image of $\rho_i$.

### Complex Plane

The definition carries over to the complex plane, in which context it is usually applied:

Let $C$ be a contour in $\C$ defined by the (finite) sequence $\sequence {C_1, \ldots, C_n}$ of directed smooth curves in $\C$.

Let $C_i$ be parameterized by the smooth path $\gamma_i: \closedint {a_i} {b_i} \to \C$ for all $i \in \set {1, \ldots, n}$.

The image of $C$ is defined as:

$\ds \Img C := \bigcup_{i \mathop = 1}^n \Img {\gamma_i}$

where $\Img {\gamma_i}$ denotes the image of $\gamma_i$.

If $\Img C \subseteq D$, where $D$ is a subset of $\C$, we say that $C$ is a contour in $D$.