From sjg at cantab.net  Thu Jan  4 21:23:48 2018
From: sjg at cantab.net (Simon Guest)
Date: Fri, 5 Jan 2018 09:23:48 +1300
Subject: [Rd] Fixed BLAS tests for external BLAS library
In-Reply-To: <d8f5a2bf-48ab-c5cc-d170-83209a79cceb@gmail.com>
References: <CAFhGSbtyd0-=FTMsE8ty0vdGvhmbTGM+Ww5+KgQpv-xFsfAq0w@mail.gmail.com>
 <d8f5a2bf-48ab-c5cc-d170-83209a79cceb@gmail.com>
Message-ID: <CAFhGSbsqEaD9OZyKBfTrbh1i11razBcPB1282kCz9b9mcBHTpQ@mail.gmail.com>

Hi Tomas,

Thanks for your reply.

I find your response curious, however.  Surely the identical() test is
simply incorrect when catering for possibly different BLAS
implementations?  Or is it the case that conformant BLAS implementations
all produce bit-identical results, which seems unlikely?  (Sorry, I am
unfamiliar with the BLAS spec.)  Although whatever the answer to this
theoretical question, the CentOS 7 external BLAS library evidently doesn't
produce bit-identical results.

If you don't agree that replacing identical() with all.equal() is clearly
the right thing to do, as demonstrated by the CentOS 7 external BLAS
library failing the test, then I think I will give up now trying to help
improve the R sources.  I simply can't justify to my client more time spent
on making this work, when we already have a local solution (which I hoped
others would be able to benefit from).  Ah well.

cheers,
Simon

On 5 January 2018 at 00:07, Tomas Kalibera <tomas.kalibera at gmail.com> wrote:

> Hi Simon,
>
> we'd need more information to consider this - particularly which
> expression gives an imprecise result with ACML and what are the computed
> values, differences. It is not common for optimized BLAS implementations to
> fail reg-BLAS.R tests, but it is common for them to report numerical
> differences in tests of various recommended packages where more complicated
> computations are done (e.g. nlme), on various platforms.
>
> Best
> Tomas
>
>
> On 12/18/2017 08:56 PM, Simon Guest wrote:
>
>> We build R with dynamically linked BLAS and LAPACK libraries, in order
>> to use the AMD Core Math Library (ACML) multi-threaded implementation
>> of these routines on our 64 core servers.  This is great, and our
>> users really appreciate it.
>>
>> However, when building like this, make check fails on the reg-BLAS.R
>> test.  The reason for this is that the expected test output is checked
>> using identical.  By changing all uses of identical in this file to
>> all.equal, the tests pass.
>>
>> Specifically, I run this command before make check:
>>
>> $ sed -i -e 's/identical/all.equal/g' tests/reg-BLAS.R
>>
>> I suggest that the test is fixed like this in the R source code.
>>
>> Here is the configure command I use, on CentOS 7:
>> $ ./configure --with-system-zlib --with-system-bzlib --with-system-pcre \
>>      --with-blas \
>>      --with-lapack \
>>      --with-tcl-config=/usr/lib64/tclConfig.sh \
>>      --with-tk-config=/usr/lib64/tkConfig.sh \
>>      --enable-R-shlib \
>>      --enable-prebuilt-html
>>
>> cheers,
>> Simon
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>
>
>

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[Rd] Fixed BLAS tests for external BLAS library
Simon Guest