@data-ui/histogram/esm/utils/kernels/epanechnikov.js

React + d3 library for creating histograms

/* eslint no-magic-numbers: 0 */

/*
 * Returns an Epanechnikov (parabolic) kernel function which takes a
 * free smoothing parameter as input.
 * code from https://gist.github.com/mbostock/4341954
 * kernel info https://en.wikipedia.org/wiki/Kernel_(statistics)
 */
export default function kernelEpanechnikov(smoothing) {
  if (smoothing === void 0) {
    smoothing = 5;
  }

  return function (val) {
    return Math.abs(val / smoothing) <= 1 ? 0.75 * ((1 - val * val) / smoothing) : 0;
  };
}