API Reference > geometry-core > Curve > Arc3d > fractionToPointAndDerivative fractionToPointAndDerivative Method Convert a fractional position to xyz coordinates and derivative with respect to fraction. fractionToPointAndDerivative(fraction: number, result?: Ray3d): Ray3d Parameter Type Description fraction number fractional position on arc result Ray3d optional preallocated result Returns - Ray3d Defined in curve/Arc3d.ts Line 319 Last Updated: 12 June, 2024