API Reference > geometry-core > Bspline > BSpline1dNd > evaluateBuffersInSpan1 evaluateBuffersInSpan1 Method Evaluate the basis functions and one derivative at spanIndex and fraction. Evaluations are stored in the preallocated this.basisBuffer Immediately do the summations of the basis values times the respective control points Summations are stored in the preallocated this.poleBuffer and this.poleBuffer evaluateBuffersInSpan1(spanIndex: number, spanFraction: number): void Parameter Type Description spanIndex number spanFraction number Returns - void Defined in core/geometry/src/bspline/BSpline1dNd.ts Line 113 Last Updated: 15 June, 2021