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Strange results with 4.2

2012-09-05
2012-09-15
  • Per Zetterberg

    Per Zetterberg - 2012-09-05

    Hi All,

    I have been running successfully with the version of IT++ packaged with ubuntu
    10.04. I then started using ubuntu 11.10 with weird results sometimes. I then
    tried building 4.2 from source with same weird results as a result. Finally
    after installing 4.0.7 I got my old results back. The weirdness manifested
    itself as e.g. different values of random variables being generated despite
    first reseting using the same seed. I know it can happen with multiple threads
    - but my code should be single thread (unless something happens that I don't
    understand).

    I am using a Dell E6410 latitude with an "Intel(R) Core(TM) i5" CPU and run
    64bit version of ubuntu 11.10.

    BR/

    Per

     
  • Per Zetterberg

    Per Zetterberg - 2012-09-05

    A second thought. The weird things I have seen have all involved binary
    numbers (bvec). Could there possibly be something related to how they are
    implemented in IT++ for 64bit processors .... just a wild guess.

     
  • Kumar Appaiah

    Kumar Appaiah - 2012-09-06

    Hi.

    I am the maintainer of the IT++ packages for Debian (and thus, Ubuntu). You
    need to give me a sample program to try out and see why this could be
    happening. That said, the first thing I'd look at is whether you are using
    vanilla lapack and blas, or the Atlas versions and whether this is causing
    some adverse effects.

    In any case, I'd suggest you try building your own version of IT++ and running
    make check to run the tests.

     

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