//
 // 摘要:
 //     Tests that the value of the named element is within a circle (see $within and
 //     $center).
 //
 // 参数:
 //   name:
 //     The name of the element to test.
 //
 //   centerX:
 //     The x coordinate of the origin.
 //
 //   centerY:
 //     The y coordinate of the origin.
 //
 //   radius:
 //     The radius of the circle.
 //
 // 返回结果:
 //     The builder (so method calls can be chained).
 public static FilterDefinition <BsonDocument> WithinCircle(string name, double centerX, double centerY, double radius)
 {
     return(filter.GeoWithinCenter(name, centerX, centerY, radius));
 }