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import { sumNthPowerDeviations } from "./sum_nth_power_deviations.ts";
/** * The [variance](http://en.wikipedia.org/wiki/Variance) * is the sum of squared deviations from the mean. * * This is an implementation of variance, not sample variance: * see the `sampleVariance` method if you want a sample measure. * * @param {number[]} x a population of one or more data points * @returns {number} variance: a value greater than or equal to zero. * zero indicates that all values are identical. * @throws {Error} if x's length is 0 * @example * variance([1, 2, 3, 4, 5, 6]); // => 2.9166666666666665 */export function variance(x: number[]): number {  if (!x.length) {    throw new Error("variance requires at least one data point");  }
  // Find the mean of squared deviations between the  // mean value and each value.  return sumNthPowerDeviations(x, 2) / x.length;}