Bug#898941: caffe-cpu: Very different results for gpu and cpu calculations due to possibly problematic BLAS dependency

[Christoph Wiedemann]

Package: caffe-cpu
Severity: important

Dear Maintainer,

I'm getting very different results in cpu mode compared to gpu mode, when using the libblas3 (version 3.7.0-2) package. 
After installing the libopenblas-base package (version 0.2.19-3) the problems disappeared. I don't know whether
this is a dependency problem of the package or it is a known problem in libblas3. I was able to uninstall and install
libopenblas-base while libblas3 was still being installed, which is a little bit confusing to me.

Note that I reported the bug initially here: https://github.com/twhui/MSG-Net/issues/2

Note also that this bug has been found with a recompiled package with matlab support enabled. I used this howto
https://github.com/BVLC/caffe/blob/master/docs/install_apt_debian.md, and changed only the matlab options. However, 
I don't think that the behaviour is visible in matlab only, though I didn't try this.

Kind Regards
Christoph

-- System Information:
Debian Release: 9.4
  APT prefers stable
  APT policy: (1000, 'stable'), (900, 'stable'), (500, 'stable-updates')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.9.0-6-amd64 (SMP w/8 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages caffe-cpu depends on:
pn  caffe-tools-cpu                  <none>
ii  libblas3 [libblas.so.3]          3.7.0-2
pn  libcaffe-cpu1                    <none>
ii  libopenblas-base [libblas.so.3]  0.2.19-3
pn  python3-caffe-cpu                <none>

caffe-cpu recommends no packages.

Versions of packages caffe-cpu suggests:
pn  caffe-doc         <none>
pn  libcaffe-cpu-dev  <none>