# Method GetConvergenceAngle

#### GetConvergenceAngle(MapPoint)

Calculates the grid convergence for a spatial reference at a given point.

##### Declaration

`public double GetConvergenceAngle(MapPoint point)`

##### Parameters

Type | Name | Description |
---|---|---|

MapPoint | point | The point |

##### Returns

Type | Description |
---|---|

System.Double | The grid convergence in degrees. |

##### Remarks

The grid convergence is the angle between True North and Grid North at a point on a map. The grid convergence can be used to convert a horizontal direction expressed as an azimuth in a geographic coordinate system (relative to True North) to a direction expressed as a bearing in a projected coordinate system (relative to Grid North), and vice versa. Sign convention The grid convergence returned by this method is positive when Grid North lies east of True North. The following formula demonstrates how to obtain a bearing ( b ) from an azimuth ( a ) using the grid convergence ( c ) returned by this method: b = a - c This sign convention is sometimes named the Gauss-Bomford convention. Other notes Returns 0 if the spatial reference is a geographic coordinate system. Returns NAN if the point is outside the projection's horizon. If the point has no spatial reference, it is assumed to be in the given spatial reference. If the point's spatial reference differs from the spatial reference given, its location is transformed automatically to the given spatial reference.

### Applies to

## Platforms and versions

Target | Versions |
---|---|

.NET Standard 2.0 | 100.3 - 200.4 |

.NET | 100.13 - 200.4 |

.NET Windows | 100.13 - 200.4 |

.NET Android | 200.0 - 200.4 |

.NET iOS | 200.0 - 200.4 |

.NET Framework | 100.3 - 200.4 |

Xamarin.Android | 100.3 - 100.15 |

Xamarin.iOS | 100.3 - 100.15 |

UWP | 100.3 - 200.4 |