fdo-mirrors/cairo
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/cairo/cairo.git synced 2026-01-06 14:20:19 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

perf/stats: Avoid overflow when summing time-squared

Browse source 
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Chris Wilson 2011-09-13 09:40:35 +01:00
parent 8218f5278e
commit 05a73434fc
1 changed files with 6 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
perf/cairo-stats.c
View file

@ -35,6 +35,7 @@ _cairo_stats_compute (cairo_stats_t *stats,
cairo_time_t sum, mean, delta, q1, q3, iqr;
cairo_time_t outlier_min, outlier_max;
int i, min_valid, num_valid;
double s;
assert (num_values > 0);
@ -83,13 +84,11 @@ _cairo_stats_compute (cairo_stats_t *stats,
sum = _cairo_time_add (sum, values[i]);
mean = sum / num_valid;
sum = 0;
/* Let's use a normalized std. deviation for easier comparison. */
s = 0;
for (i = min_valid; i < min_valid + num_valid; i++) {
delta = values[i] - mean;
sum += delta * delta;
double delta = (values[i] - mean) / (double)mean;
s += delta * delta;
}
/* Let's use a std. deviation normalized to the mean for easier
* comparison. */
stats->std_dev = sqrt(sum / num_valid) / mean;
stats->std_dev = sqrt(s / num_valid);
}