/* -------------------------------------------------------------------------   * 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.c  (Univariate Statistics) * Authors           : Steve Park & Dave Geyer  * Language          : ANSI C  * Latest Revision   : 9-28-98 * -------------------------------------------------------------------------  */#include <stdio.h>                             #include <math.h>                                  int main(void){  long    index;  double  data;  double  sum = 0.0;  double  mean;  double  stdev;  double  min;  double  max;  double  diff;  scanf("%lf\n", &data);  if (!feof(stdin)) {    index  = 1;    mean   = data;    min    = data;    max    = data;  }  else     index = 0;  while (!feof(stdin)) {    scanf("%lf\n", &data);    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;  }  if (index > 0) {    stdev = sqrt(sum / index);    printf("\nfor a sample of size %ld\n", index);    printf("mean ................. = %7.3f\n", mean);    printf("standard deviation ... = %7.3f\n", stdev);    printf("minimum .............. = %7.3f\n", min);    printf("maximum .............. = %7.3f\n", max);  }  return (0);}