API Reference > geometry-core > Bspline > BSpline1dNd > sumPoleBuffer1ForSpan sumPoleBuffer1ForSpan Method sum poles at span spanIndex by the weights in the poleBuffer1, i.e. form first derivatives sumPoleBuffer1ForSpan(spanIndex: number): void Parameter Type Description spanIndex number Returns - void Defined in core/geometry/src/bspline/BSpline1dNd.ts Line 127 Last Updated: 15 June, 2021