numeric(tickValue, index, ticks) {
    if (tickValue === 0) {
      return '0'; // never show decimal places for 0
    }

    const locale = this.chart.options.locale;
    let notation;
    let delta = tickValue; // This is used when there are less than 2 ticks as the tick interval.

    if (ticks.length > 1) {
      // all ticks are small or there huge numbers; use scientific notation
      const maxTick = Math.max(Math.abs(ticks[0].value), Math.abs(ticks[ticks.length - 1].value));
      if (maxTick < 1e-4 || maxTick > 1e+15) {
        notation = 'scientific';
      }

      delta = calculateDelta(tickValue, ticks);
    }

    const logDelta = log10(Math.abs(delta));

    // When datasets have values approaching Number.MAX_VALUE, the tick calculations might result in
    // infinity and eventually NaN. Passing NaN for minimumFractionDigits or maximumFractionDigits
    // will make the number formatter throw. So instead we check for isNaN and use a fallback value.
    //
    // toFixed has a max of 20 decimal places
    const numDecimal = isNaN(logDelta) ? 1 : Math.max(Math.min(-1 * Math.floor(logDelta), 20), 0);

    const options = {notation, minimumFractionDigits: numDecimal, maximumFractionDigits: numDecimal};
    Object.assign(options, this.options.ticks.format);

    return formatNumber(tickValue, locale, options);
  }
Formatter for numeric ticks
@method Chart.Ticks.formatters.numeric
@param tickValue {number} the value to be formatted
@param index {number} the position of the tickValue parameter in the ticks array
@param ticks {object[]} the list of ticks being converted
@return {string} string representation of the tickValue parameter