/* -------------------------------------------------------------------------   * This program reads a (text) data file and computes the mean, minimum,  * maximum, and standard deviation.   The one-pass algorithm used is due to  * B.P. Welford (Technometrics, vol. 4, no 3, August 1962.)  * * NOTE: the text data file is assumed to be in a one-value-per-line format * with NO blank lines in the file.   The data can be either fixed point  * (integer valued), or floating point (real valued).  * * To use the program, compile it to disk to produce uvs.  Then at a command  * line prompt, uvs can be used in three ways.  * * (1) To have uvs read a disk data file, say uvs.dat (in the format above), * at a command line prompt use '<' redirection as:  * *     uvs < uvs.dat * * (2) To have uvs filter the numerical output of a program, say test, at a * command line prompt use '|' pipe as:  * *     test | uvs * * (3) To use uvs with keyboard input, at a command line prompt enter: * *      uvs * * Then enter the data -- one value per line -- being sure to remember to * signify an end-of-file.  In Unix/Linux, signify an end-of-file by * entering ^d (Ctrl-d) as the last line of input. *  * Name              : Uvs.java (Multi-Server Queue) * Authors           : Steve Park & Dave Geyer * Translated by     : Jun Wang * Language          : Java * Latest Revision   : 6-16-06 * * Program uvs       : Section 4.1, based on Algorithm 4.1.1 * ------------------------------------------------------------------------- */import java.io.*;import java.util.*;import java.text.*;class Uvs {  public static void main(String[] args) throws IOException {    long    index;    double  data;    double  sum = 0.0;    double  mean;    double  stdev;    double  min;    double  max;    double  diff;    String line;    InputStreamReader r = new InputStreamReader(System.in);    BufferedReader ReadThis = new BufferedReader(r);    index = 0;    mean  = 0.0;    min   = 0.0;    max   = 0.0;        try {      if ( (line = ReadThis.readLine()) != null) {        data  = Double.parseDouble(line);        index = 1;        mean  = data;        min   = data;        max   = data;      }      while ( (line = ReadThis.readLine()) != null ) {        data  = Double.parseDouble(line);        index++;        diff  = data - mean;        sum  += diff * diff * (index - 1.0) / index;        mean += diff / index;        if (data > max)          max = data;        else if (data < min)          min = data;      }    } catch (EOFException e) {      System.out.println("Uvs: " + e);    } catch (NumberFormatException nfe) {//      System.out.println("Uvs: " + nfe);    }    if (index > 0) {      DecimalFormat f = new DecimalFormat("###0.000");      stdev = Math.sqrt(sum / index);      System.out.println("\nfor a sample of size " + index);      System.out.println("mean ................. =  " + f.format(mean));      System.out.println("standard deviation ... =  " + f.format(stdev));      System.out.println("minimum .............. =  " + f.format(min));      System.out.println("maximum .............. =  " + f.format(max));    }  }}