nickr523

dposv gives different answers based on the alignment of the memory of the arrays.

Discussion created by nickr523 on May 30, 2013
Latest reply on Jun 6, 2013 by chipf

I am wondering if you would expect dposv to give different answers based on the alignment of the memory of the arrays passed to it.  I am seeing differences when the arrays are 8 byte aligned versus 16 byte aligned.  I am only seeing this difference when I run on an AMD 6344 processor and only with the gfortran64 library.  gfortran64_fma4 produces stable answers independent of memory alignment.  I am using acml 5.3.1.  I have tried this on a Centos 6.4 and an Ubuntu system with an AMD 6344 processors and saw the same stability issue.  I have tried running the same executable on several different older AMD and Intel processors and get stable results.

 

Is this a bug?  Is there someway to control dposv to give stable answers independent of memory alignment?

 

Thanks for your help,

 

/Nick

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