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发表于 2009-2-20 21:24:01
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原帖由 wzd811 于 2009-2-20 20:19 发表 
话说记得lhc的一个老外说过同样的sixtrack经过不同处理器运算,不单运算时间,连结果都是天差地别,神奇阿…
请问还记得原文在哪里麽?比较感兴趣
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update:参考资料在这里,感谢fwj~
http://www.equn.com/forum/viewthread.php?tid=7698
http://www.equn.com/forum/viewthread.php?tid=7719
http://boinc.equn.com/lhc/LHCathome/athome.html
http://lhcathome.cern.ch/athome/athome.shtml
Besides helping build the LHC, LHC@home is helping to provide some fundamental insights into the challenges of distributed computing.
Both with LHC@home, and with an in-house precursor called CPSS, it was discovered that different processors can produce sometimes markedly different results.
This is due to the ways that certain mathematical functions such as exponential and tangent handle rounding errors on different processors.
The lack of an internationally accepted standard for this, combined with the often chaotic nature of the particle orbits in the SixTrack simulations,
which tend to amplify even the smallest differences, can produce significantly different results on different computers. Although initially perceived
as a setback, this problem can be dealt with using newly developed function libraries from a group at the Ecole Nationale Supérieure in Lyon.
The result also provides a potentially important insight for those currently developing applications for Grid computing, since ultimately these will
also have to run on a wide range of computers.
[ 本帖最后由 Julian_Yuen 于 2009-2-20 22:31 编辑 ] |
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