cdh.c

Simulation Modeling,Discrete Event Simulation,Statistical Analysis of Simulation Models

/* ------------------------------------------------------------------------
 * This program illustrates an array-based algorithm for tallying a 
 * continuous-data histogram for data read from standard input (stdin).
 * Like program uvs, a compiled version of this program supports file
 * redirection.
 *
 * The MIN, MAX, K parameters are "tuned" to the datafile uvs.dat.
 * For other datafiles these parameters must be adjusted -- you might
 * want to process the datafile with program uvs first to get a handle on
 * appropriate values for these three parameters.
 * 
 * Name              : cdh.c  (Continuous Data Histogram)
 * Authors           : Steve Park & Dave Geyer
 * Language          : ANSI C
 * Latest Revision   : 12-27-95
 * ------------------------------------------------------------------------ 
 */

#include <stdio.h>
#include <math.h> 

#define  MIN     0.0
#define  MAX     8.0
#define  K       16                          /* number of histogram bins   */
#define  DELTA   ((MAX - MIN) / K)           /* histogram bin size (width) */
#define  sqr(x)  ((x) * (x))


  int main(void)
{
  double x;                                      /* data value          */
  long   j;                                      /* histogram bin index */
  long   index    = 0;                           /* sample size         */
  long   count[K] = {0.0};                       /* bin count           */
  double midpoint[K];                            /* bin midpoint        */
  struct {                                       
    long lo;
    long hi;
  } outliers      = {0, 0};
  double sum      = 0.0;
  double sumsqr   = 0.0;
  double mean;
  double stdev;

  for (j = 0; j < K; j++) 
    midpoint[j] = MIN + (j + 0.5) * DELTA;

  while (!feof(stdin)) {                         /* tally the data */
    scanf("%lf\n", &x);
    index++;
    if ((x >= MIN) && (x < MAX)) {
      j = (long) ((x - MIN) / DELTA);
      count[j]++;
    }
    else if (x < MIN)
      outliers.lo++;
    else
      outliers.hi++;
  }

  for (j = 0; j < K; j++)                        /* histogram mean */
    sum += midpoint[j] * count[j];
  mean   = sum / index;

  for (j = 0; j < K; j++)                        /* histogram stdev */
    sumsqr += sqr(midpoint[j] - mean) * count[j];
  stdev     = sqrt(sumsqr / index);

  printf("  bin     midpoint     count   proportion    density\n\n");
  for (j = 0; j < K; j++) { 
    printf("%5ld", j + 1);                                    /* bin        */
    printf("%12.3f", midpoint[j]);                            /* midpoint   */
    printf("%10ld", count[j]);                                /* count      */
    printf("%12.3f", (double) count[j] / index);              /* proportion */
    printf("%12.3f\n", (double) count[j] / (index * DELTA));  /* density    */
  }
  printf("\nsample size .... = %7ld\n", index);
  printf("mean ........... = %7.3f\n", mean);
  printf("stdev .......... = %7.3f\n\n", stdev);
  if (outliers.lo > 0)
    printf("NOTE: there were %ld low outliers\n", outliers.lo);
  if (outliers.hi > 0)
    printf("NOTE: there were %ld high outliers\n", outliers.hi);

  return (0);
}