Hi Asad,
>> I
>> found that running the same source code on these OS, with the same
>> versions of of gcc and open-mpi installed on them, gives different
>> results than Fedora and Ubuntu after a few hundred iterations. The first
>> few hundered iterations are exactly similar to that of Fedora and
>> Ubuntu but then it starts giving different results.
> Are you also using the same hardware? Different hardware platforms may
> exhibit different rounding behaviour. After some dependent interations
> such effects might indeed sum up and yield different results. The issue
> is called numeric (in)stability and is not specifically related to openmpi.
Yes I use different machines such as
machine 1 uses AMD Opterons. (Fedora)
machine 2 and 3 use Intel Xeons. (CentOS)
machine 4 uses slightly older Intel Xeons. (Debian)
Only machine 1 gives correct results. While CentOS and Debian results are same but are wrong and different from those of machine 1.
Cheers,
Asad