code: function meanAbsolutePercentageError(actuals, estimates) {
                const errors = forecastErrors(actuals, estimates).map(e=>Math.abs(e));
                const absErrorPercent = errors.map((e, i) => e / actuals[ i ]);
                return avg$2(absErrorPercent);
              }
docs: MAPE (Mean Absolute Percent Error) measures the size of the error in percentage terms
  @memberOf util
  @see {@link https://www.forecastpro.com/Trends/forecasting101August2011.html}
  @example
  const actuals = [ 45, 38, 43, 39 ];
  const estimates = [ 41, 43, 41, 42 ];
  const MAPE = ms.util.meanAbsolutePercentageError(actuals, estimates);
  MAPE.toFixed(2) // => 0.86
  @param {Number[]} actuals - numerical samples
  @param {Number[]} estimates - estimates values
  @returns {Number} MAPE