text: /* *
   * (c) 2010-2018 Highsoft AS
   *
   * Author: Sebastian Domas
   *
   * License: www.highcharts.com/license
   */
  
  'use strict';
  
  import H from '../parts/Globals.js';
  import '../parts/Utilities.js';
  import derivedSeriesMixin from '../mixins/derived-series.js';
  
  var seriesType = H.seriesType,
      correctFloat = H.correctFloat,
      isNumber = H.isNumber,
      merge = H.merge;
  
  
  /* ************************************************************************** *
   *  BELL CURVE                                                                *
   * ************************************************************************** */
  
  function mean(data) {
      var length = data.length,
          sum = data.reduce(function (sum, value) {
              return (sum += value);
          }, 0);
  
      return length > 0 && sum / length;
  }
  
  function standardDeviation(data, average) {
      var len = data.length,
          sum;
  
      average = isNumber(average) ? average : mean(data);
  
      sum = data.reduce(function (sum, value) {
          var diff = value - average;
          return (sum += diff * diff);
      }, 0);
  
      return len > 1 && Math.sqrt(sum / (len - 1));
  }
  
  function normalDensity(x, mean, standardDeviation) {
      var translation = x - mean;
      return Math.exp(
          -(translation * translation) /
          (2 * standardDeviation * standardDeviation)
      ) / (standardDeviation * Math.sqrt(2 * Math.PI));
  }
  
  
  /**
   * Bell curve class
   *
   * @private
   * @class
   * @name Highcharts.seriesTypes.bellcurve
   *
   * @augments Highcharts.Series
   *
   * @mixes DerivedSeriesMixin
   */
  seriesType('bellcurve', 'areaspline'
  
  /**
   * A bell curve is an areaspline series which represents the probability density
   * function of the normal distribution. It calculates mean and standard
   * deviation of the base series data and plots the curve according to the
   * calculated parameters.
   *
   * @sample {highcharts} highcharts/demo/bellcurve/
   *         Bell curve
   *
   * @extends      plotOptions.areaspline
   * @since        6.0.0
   * @product      highcharts
   * @excluding    boostThreshold, connectNulls, stacking, pointInterval,
   *               pointIntervalUnit
   * @optionparent plotOptions.bellcurve
   */
  , {
     /**
      * This option allows to define the length of the bell curve. A unit of the
      * length of the bell curve is standard deviation.
      *
      * @sample highcharts/plotoptions/bellcurve-intervals-pointsininterval
      *         Intervals and points in interval
      */
      intervals: 3,
  
     /**
      * Defines how many points should be plotted within 1 interval. See
      * `plotOptions.bellcurve.intervals`.
      *
      * @sample highcharts/plotoptions/bellcurve-intervals-pointsininterval
      *         Intervals and points in interval
      */
      pointsInInterval: 3,
  
      marker: {
          enabled: false
      }
  
  }, merge(derivedSeriesMixin, {
      setMean: function () {
          this.mean = correctFloat(mean(this.baseSeries.yData));
      },
  
      setStandardDeviation: function () {
          this.standardDeviation = correctFloat(
              standardDeviation(this.baseSeries.yData, this.mean)
          );
      },
  
      setDerivedData: function () {
          if (this.baseSeries.yData.length > 1) {
              this.setMean();
              this.setStandardDeviation();
              this.setData(
                  this.derivedData(this.mean, this.standardDeviation), false
              );
          }
      },
  
      derivedData: function (mean, standardDeviation) {
          var intervals = this.options.intervals,
              pointsInInterval = this.options.pointsInInterval,
              x = mean - intervals * standardDeviation,
              stop = intervals * pointsInInterval * 2 + 1,
              increment = standardDeviation / pointsInInterval,
              data = [],
              i;
  
          for (i = 0; i < stop; i++) {
              data.push([x, normalDensity(x, mean, standardDeviation)]);
              x += increment;
          }
  
          return data;
      }
  }));
  
  
  /**
   * A `bellcurve` series. If the [type](#series.bellcurve.type) option is not
   * specified, it is inherited from [chart.type](#chart.type).
   *
   * For options that apply to multiple series, it is recommended to add
   * them to the [plotOptions.series](#plotOptions.series) options structure.
   * To apply to all series of this specific type, apply it to
   * [plotOptions.bellcurve](#plotOptions.bellcurve).
   *
   * @extends   series,plotOptions.bellcurve
   * @since     6.0.0
   * @product   highcharts
   * @excluding dataParser, dataURL, data
   * @apioption series.bellcurve
   */
  
  /**
   * An integer identifying the index to use for the base series, or a string
   * representing the id of the series.
   *
   * @type      {number|string}
   * @apioption series.bellcurve.baseSeries
   */
  