Re: Octave 3.6.4 VS2010 and the C++ API

[Michael Goffioul]

On Thu, Sep 26, 2013 at 5:20 AM, Mike Puglia <address@hidden> wrote:

Thanks again for all the help.  I tried all of the libraries and the problem seems to be limited to OpenBLAS.  I've tried this on three machines now (running XP or Windows Server 2008), and so it seems to be universal. The other three BLAS libraries in the distribution (generic, Intel SSE3 and SSE3 multi-threaded) all calculated correctly, but with a hit to performance.  On the Intel libraries the performance hit was about 25% and the generic was 2x on my machine.  Most of my work involves running things that take on the order of 1 or 2 days, so this is pretty costly.

On a somewhat related note, I'm also having problems running OpenBLAS on Amazon EC2.  It seems that the virtual machines there don't support AVX, and so OpenBLAS is defaulting to a backup (Nehalem?) that can run without AVX, which causes a performance hit of about 2x.

Do you see any alternatives to using OpenBLAS here (ATLAS maybe?) or can you suggest a fix?  Any advice you have would be greatly appreciated.

I'll have to dig into OpenBLAS code and fix the issue, but I'm pretty sure this is a calling convention mismatch between GCC and MSVC. In the meantime, you can use the "Intel SSE3" or "Intel SSE3 multi-threaded", which are ATLAS versions. I don't have any other fix to suggest.

Michael.