On Fri, Jul 25, 2008 at 5:29 PM, Bruno Lalande <bruno.lalande@gmail.com> wrote:
What platform is that?
A very common one: Linux 2.6 with GCC 4.1 or 4.2. The distribution is Kubuntu.
timer().elapsed_max() gives 2147.48 on this platform and indeed, elapsed() returns negative numbers above that time (before returning to 0).
I had thought about the possibility of making a policy-based version of boost::timer, with something like a "heart policy" that would define the way in which the time would be obtained and stored internally. There would be a portable one (the one of boost::timer currently), another one based on boost::date_time, and why not some platform-specific ones (QueryPerformanceCounter on windows for instance). But I never had the time to dig more :-(
I don't mean to hijack the thread but please let me share another way to use timer, with C, not C++ or boots. In the code, not only the time of one test, but average time, and its standard derivation are calculated so we will know how "close" is the average time. My question: Is there any similar implementation in boost? The code is as follows: int count = 30; long long times[count]; for (i = 0; i < count; i++) ｛ time start; gettimeofday (&start, NULL); // do something gettimeofday (&end, NULL); long long time = ((end.tv_sec - start.tv_sec) * 1000000 + (end.tv_usec - start.tv_usec)); times[i] = time; } // and use it printf("mean: %f, stddev: %f\n", mean(times, 20), stddev(times, 20); double variance (long long *x, int n) { double m = x[0]; double s = 0; int i; for (i = 0; i < n; i++) { double m_new = m + (x[i] - m) / (i + 1); s = s + (x[i] - m) * (x[i] - m_new); m = m_new; } return s / (n - 1); } double mean (long long *x, int n) { double m = x[0]; int i; for (i = 0; i < n; i++) { m = m + (x[i] - m) / (i + 1); } return m; } double stddev (long long *x, int n) { return sqrt (variance (x, n)); } -- Best Regards, Nguyen Hung Vu ( Nguyễn Vũ Hưng ) vuhung16plus{remove}@gmail.dot.com <vuhung16plus%7Bremove%7D@gmail.dot.com>, YIM: vuhung16 , Skype: vuhung16dg Japan through an eye of a gaijin: http://www.flickr.com/photos/vuhung/tags/fav/