Bug#1117208: python3-numpy: Can't find libblas and liblapack

[Matthias Urlichs]

On 04.10.25 23:42, Simon McVittie wrote:
> Control: reassign -1 libblas3 3.12.1-6
> Control: affects -1 + python3-numpy
> Control: tags -1 + moreinfo
>
> On Sat, 04 Oct 2025 at 22:00:13 +0200, Matthias Urlichs wrote:
>> I had to do this:
>>
>> /usr/lib/x86_64-linux-gnu$ sudo ln -s blas/libblas.so.3 .
>> /usr/lib/x86_64-linux-gnu$ sudo ln -s lapack/liblapack.so.3 .
>>
>> ... to get a plain "import numpy" to work.
>
> This sounds like a problem with the libblas.so.3 alternative. The way 
> it is meant to work is something like this:
>
> /usr/lib/x86_64-linux-gnu/libblas.so.3
> -> /etc/alternatives/libblas.so.3-x86_64-linux-gnu
> -> /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3
>
Ah, so that's the clue I was missing.

# update-alternatives --query libblas.so.3-x86_64-linux-gnu
update-alternatives: warning: alternative 
/usr/lib/x86_64-linux-gnu/atlas/libblas.so.3 (part of link group 
libblas.so.3-x86_64-linux-gnu) doesn't exist; removing from list of 
alternatives
Name: libblas.so.3-x86_64-linux-gnu
Link: /usr/lib/x86_64-linux-gnu/libblas.so.3
Status: auto
Best: /usr/lib/x86_64-linux-gnu/blas/libblas.so.3
Value: /usr/lib/x86_64-linux-gnu/atlas/libblas.so.3

Alternative: /usr/lib/x86_64-linux-gnu/blas/libblas.so.3
Priority: 10

So what actually happened seems to be that atlas, upon deinstallation, 
somehow failed to remove its alternative correctly ..?

-- 
-- Matthias Urlichs