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##### return_centroid

Calculates the centroid of a geometry.

###### Description

The free function centroid calculates the geometric center (or: center of mass) of a geometry. This version with the return_ prefix returns the centroid, and a template parameter must therefore be specified in the call..

###### Synopsis

    template<typename Point, typename Geometry>
    Point return_centroid(Geometry const & geometry)

###### Parameters

Type | Concept | Name | Description
--- | --- | --- | ---
Point | Any type fulfilling a Point Concept | - | Must be specified
Geometry const & | Any type fulfilling a Geometry Concept | geometry | A model of the specified concept

###### Returns

The calculated centroid

###### Header

Either

`#include <boost/geometry/geometry.hpp>`

Or

`#include <boost/geometry/algorithms/centroid.hpp>`

###### Conformance

The function centroid implements function Centroid from the OGC Simple Feature Specification.

###### Behavior

Case | Behavior
--- | ---
Point | Returns the point itself as the centroid
Multi Point | Calculates centroid (based on average)
linear (e.g. linestring) | Calculates centroid (based on weighted length)
areal (e.g. polygon) | Calculates centroid
Empty (e.g. polygon without points) | Throws a centroid_exception
Cartesian | Implemented
Spherical | Calculates the centroid as if based on Cartesian coordinates

###### Supported geometries

| 2D | 3D
--- | --- | ---
Point |  |
Segment |  |
Box |  |
Linestring |  |
Ring |  |
Polygon |  |
MultiPoint |  |
MultiLinestring |  |
MultiPolygon |  |

###### Complexity

Linear