On 2011-12-20 12:16:34 +0100, Vincent Lefevre wrote: > Now, the test program is faster where the values are *closer* to 0. > This contradicts what you say about subnormals. Actually, after thinking a bit more about it, there are also more operations on the subnormals in the case 0.9, so that the subnormals could also be a problem, and indeed: ypig:~> time ./a.out 0.9999999 ./a.out 0.9999999 0.10s user 0.00s system 92% cpu 0.108 total ypig:~> time ./a.out 0.9 ./a.out 0.9 2.93s user 0.00s system 98% cpu 2.987 total ypig:~> time ./a.out 0.1 ./a.out 0.1 0.10s user 0.00s system 86% cpu 0.116 total The fact that only the second case is slower tends to indicate that the problem is the subnormals (whether they are implemented in software and in hardware). -- Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / Arénaire project (LIP, ENS-Lyon)
