/* ------------------------------------------------------------------------ * 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);}