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计算数组的（偏差校正后的样本）标准偏差。
//package com.nowjava; /** 来 自 n o w j a v a . c o m - 时 代 Java**/ public class Main { public static void main(String[] argv) throws Exception { double[] v = new double[] { 34.45, 35.45, 36.67, 37.78, 37.0000, 37.1234, 67.2344, 68.34534, 69.87700 }; System.out.println(standardDeviation(v)); } /** * Computes the (bias-corrected sample) standard deviation of an array. */ public static double standardDeviation(double[] v) { return (Math.sqrt(variance(v))); } /** * Returns the (bias-corrected sample) standard deviation of an array. */ public static double standardDeviation(int[] v) { return (Math.sqrt(variance(v))); }//from 时 代 J a v a - nowjava.com /** * Computes the (bias-corrected sample) variance. */ public static double variance(double[] v) { if (v.length > 1) { final double m = mean(v); double ans = 0.0; for (int i = 0; i < v.length; i++) ans += (v[i] - m) * (v[i] - m); return ans / (v.length - 1); } else throw new IllegalArgumentException( "Array length must be of 2 or greater."); } /** * Computes the (bias-corrected sample) variance. */ public static double variance(int[] v) { if (v.length > 1) { final double m = mean(v); double ans = 0.0; for (int i = 0; i < v.length; i++) ans += (v[i] - m) * (v[i] - m); return ans / (v.length - 1); } else throw new IllegalArgumentException( "Array length must be of 2 or greater."); } /** * Computes the mean. */ public static double mean(double[] v) { if (v.length == 0) throw new IllegalArgumentException( "Nothing to compute! The array must have at least one element."); return (mass(v) / (double) v.length); } /** * Computes the mean. */ public static double mean(int[] v) { if (v.length == 0) throw new IllegalArgumentException( "Nothing to compute! The array must have at least one element."); return (mass(v) / (double) v.length); } /** * Returns the sum of the elements of the array. */ public static