A DSegment3d is created from a StartPoint and EndPoint.

	DSegment3d(ref DPoint3d StartPoint, ref DPoint3d EndPoint)
	DSegment3d(double ax, double ay, double xz, double
bx, double by, double bz)

Closest Fraction And Point

	ClosestFractionAndPoint(ref DPoint3d SpacePoint, bool
bounded, out double fraction, out DPoint3d ClosePoint)
	ClosestFractionAndPoint(ref DPoint3d SpacePoint, bool
bounded0, bool bounded1, out double fraction, out DPoint3d ClosePoint)

STATIC method IntersectXY

	DSegment3d.IntersectXY(ref DSegment3d lineA, ref DSegment3d
lineB, out double fractionA, out DPoint3d pointA, out double fractionB,
out DPoint3d pointB)

STATIC method ClosestApproachSegment

	DSegment3d.ClosestApproachSegment(ref DSegment3d lineA,
ref DSegment3d lineB, out DSegment3d segment, out double fractionA,
out double fractionB)

Point at Fraction

	Fraction(fraction)
	PointAtFraction(double fraction, out DVector3d Derivative1)
	PointAtFraction(doube fraction, out DVector3d Derivative1,
out DVector3d Derivative2)

To extract a vector from a DSegment3d use the Extent property:

	Extent()