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/** * The [Geometric Mean](https://en.wikipedia.org/wiki/Geometric_mean) is * a mean function that is more useful for numbers in different * ranges. * * This is the nth root of the input numbers multiplied by each other. * * The geometric mean is often useful for * **[proportional growth](https://en.wikipedia.org/wiki/Geometric_mean#Proportional_growth)**: given * growth rates for multiple years, like _80%, 16.66% and 42.85%_, a simple * mean will incorrectly estimate an average growth rate, whereas a geometric * mean will correctly estimate a growth rate that, over those years, * will yield the same end value. * * This runs on `O(n)`, linear time in respect to the array * * @param {number[]} x sample of one or more data points * @returns {number} geometric mean * @throws {Error} if x is empty * @throws {Error} if x contains a negative number * @example * geometricMean([1.80, 1.166666, 1.428571]); */export function geometricMean(x: number[]): number {  if (!x.length) {      throw new Error("geometricMean requires at least one data point");  }
  // the starting value.  let value = 1;
  for (let i = 0; i < x.length; i++) {      // the geometric mean is only valid for positive numbers      if (x[i] <= 0) {          throw new Error(              "geometricMean requires only positive numbers as input"          );      }
      // repeatedly multiply the value by each number      value *= x[i];  }
  return Math.pow(value, 1 / x.length);}