API Reference > geometry-core > Bspline > BSpline1dNd > sumPoleBuffer2ForSpan sumPoleBuffer2ForSpan Method sum poles at span spanIndex by the weights in the poleBuffer2, i.e. form second derivatives sumPoleBuffer2ForSpan(spanIndex: number): void Parameter Type Description spanIndex number Returns - void Defined in core/geometry/src/bspline/BSpline1dNd.ts Line 137 Last Updated: 15 June, 2021