lib/ccan/tally/test/run-median.c

   1 #include <ccan/tally/tally.c>
   2 #include <ccan/tap/tap.h>
   3
   4 int main(void)
   5 {
   6         int i;
   7         struct tally *tally = tally_new(100);
   8         ssize_t min, max, median;
   9         size_t err;
  10
  11         max = (ssize_t)~(1ULL << (sizeof(max)*CHAR_BIT - 1));
  12         min = (ssize_t)(1ULL << (sizeof(max)*CHAR_BIT - 1));
  13
  14         plan_tests(100*2 + 100*2 + 100*2);
  15         /* Simple median test: should always be around 0. */
  16         for (i = 0; i < 100; i++) {
  17                 tally_add(tally, i);
  18                 tally_add(tally, -i);
  19                 median = tally_approx_median(tally, &err);
  20                 ok1(err <= 4);
  21                 ok1(median - (ssize_t)err <= 0 && median + (ssize_t)err >= 0);
  22         }
  23
  24         /* Works for big values too... */
  25         for (i = 0; i < 100; i++) {
  26                 tally_add(tally, max - i);
  27                 tally_add(tally, min + 1 + i);
  28                 median = tally_approx_median(tally, &err);
  29                 /* Error should be < 100th of max - min. */
  30                 ok1(err <= max / 100 * 2);
  31                 ok1(median - (ssize_t)err <= 0 && median + (ssize_t)err >= 0);
  32         }
  33         free(tally);
  34
  35         tally = tally_new(10);
  36         for (i = 0; i < 100; i++) {
  37                 tally_add(tally, i);
  38                 median = tally_approx_median(tally, &err);
  39                 ok1(err <= i / 10 + 1);
  40                 ok1(median - (ssize_t)err <= i/2
  41                     && median + (ssize_t)err >= i/2);
  42         }
  43         free(tally);
  44
  45         return exit_status();
  46 }