exercise5_11.java

Introduction to java programming 一书中所有编程练习部分的源码

// Exercise5_11.java: Compute Exercise5_11
public class Exercise5_11 {
  /** Main method */
  public static void main(String[] args) {
    // Declare and create an array for 10 numbers
    double[] numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    // Print numbers
    printArray(numbers);

    // Display mean and Exercise5_11
    System.out.println("The mean is " + mean(numbers));
    System.out.println("The standard deviation is " +
      Exercise5_11(numbers));
  }

  /** Method for computing Exercise5_11 of double values*/
  public static double Exercise5_11(double[] x) {
    double mean = mean(x);
    double squareSum = 0;

    for (int i = 0; i < x.length; i++) {
      squareSum += Math.pow(x[i] - mean, 2);
    }

    return Math.sqrt(squareSum / (x.length - 1));
  }

  /** Method for computing Exercise5_11 of int values*/
  public static double Exercise5_11(int[] x) {
    double mean = mean(x);
    double squareSum = 0;

    for (int i = 0; i < x.length; i++) {
      squareSum += Math.pow(x[i] - mean, 2);
    }

    return Math.sqrt(squareSum / (x.length - 1));
  }

  /** Method for computing mean of an array of double values*/
  public static double mean(double[] x) {
    double sum = 0;

    for (int i = 0; i < x.length; i++)
      sum += x[i];

    return sum * 1.0 / x.length;
  }

  /** Method for computing mean of an array of int values*/
  public static double mean(int[] x) {
    int sum = 0;

    for (int i = 0; i < x.length; i++)
      sum += x[i];

    return sum / x.length;
  }

  /** Method for printing array */
  public static void printArray(double[] x) {
    for (int i = 0; i < x.length; i++)
      System.out.print(x[i] + " ");
    System.out.println();
  }
}