API Reference > geometry-core > Curve > LineString3d > fractionToPointAndDerivative fractionToPointAndDerivative Method Evaluate a point a fractional position and derivative with respect to fraction along this linestring. See LineString3d class comments for description of how fraction relates to the linestring points. fractionToPointAndDerivative(fraction: number, result?: Ray3d): Ray3d Parameter Type Description fraction number fractional position result Ray3d optional result Returns - Ray3d Defined in core/geometry/src/curve/LineString3d.ts Line 528 Last Updated: 13 June, 2024