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Re: [Question #232113]: nummerical error through multiple replications

 

Question #232113 on Yade changed:
https://answers.launchpad.net/yade/+question/232113

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hello Matthias,

what quantities and values do you consider "not disregardable"? The
multithreading might not be the only reason, just some more that came to my
mind:
- time step (if you decrease time step, it might help)
- initial state (e.g. particle positions) - what technique are you using?
might this be the source?

for your second question, see top of yade/lib/base/Math.hpp. If you want to
use "long double" instead of "double", compile Yade with cmake option
-DCMAKE_CXX_FLAGS="-DQUAD_PRECISION"
Personally I haven't try it, so I can't guarantee the result :-)

cheers
Jan



2013/7/9 matthias <question232113@xxxxxxxxxxxxxxxxxxxxx>

> New question #232113 on Yade:
> https://answers.launchpad.net/yade/+question/232113
>
> i have not disregardable numerical error in my simulationes between some
> replications caused by this described multithreading issue. running some
> replications would solve the problem but it burns so much cpu time, so it
> is not feasable.
>
> another way could be to use the 80bit long double  of the cpu (core i7).
> how can i compile yade to using this long double data type? or maybe
> double-double arithmetics?
>
> matthias
>
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