Output arguments are defined as 'out'. In the example below, A DRay3d is tested to find the closest point on the DRay3d to a point in space. Bounded is input as a boolean to determine where the DRay3d is treated as an infinite line or with a startPoint and endPoint, and the fraction along the DRay3d is an 'out' argument along with the closestPoint.

	rayD3d.ClosestFractionAndPoint(ref DPoint3d SpacePoint,
bool Bounded, out double fraction, out DPoint3d ClosePoint)

Out variables must be initialized before calling the method with out values.

	double fraction;
	DPoint3d closePoint   
	rayD3d.ClosestFractionAndPoint(ref spacePoint, bounded,
out fraction, out closePoint);