main/src/georegression/geometry/UtilLine2D_F64.java
public static LineParametric2D_F64 convert( LineSegment2D_F64 src , LineParametric2D_F64 ret )
	{
		if( ret == null )
			ret = new LineParametric2D_F64();

		ret.p.set(src.a);
		ret.slope.set(src.slopeX(),src.slopeY());

		return ret;
	}
public static LineParametric2D_F64 convert( LineSegment2D_F64 src , LineParametric2D_F64 ret )
	{
		if( ret == null )
			ret = new LineParametric2D_F64();

		ret.p.set(src.a);
		ret.slope.set(src.slopeX(),src.slopeY());

		return ret;
	}
Converts a line segment into a parametric line.  The start point will be 'src.a' and the
direction will be in the direction of 'src.b-src.a'

@param src (input) line segment
@param ret (output) line in parametric notation.  If null a new instance will be created.
@return Converted line in parametric notation