How do libatlas3, liblapacke, and libopenblas0 interact with eachother?

Question

I'm trying to figure out the interaction between the following library packages in Debian 11 and Ubuntu 20.04:

• libatlas3-base
• liblapacke
• OpenBLAS
  • libopenblas0-openmp
  • libopenblas0-pthread
  • libopenblas0-serial

It looks like the OpenBLAS packages can only be used one at a time because they are in different subdirs shown here. How do I select the active one?

• /usr/lib/x86_64-linux-gnu/openblas-openmp/libopenblas.so.0
• /usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblas.so.0
• /usr/lib/x86_64-linux-gnu/openblas-serial/libopenblas.so.0

Once I've selected the active OpenBLAS implementation, will libatlas3 or liblapacke use the active implementation? How can you tell what they are using?

Answer 1

• Libraries are selected with alternatives:

  • ~# update-alternatives --config libblas.so.3-x86_64-linux-gnu
  • ~# update-alternatives --config liblapack.so.3-x86_64-linux-gnu

• liblapacke.so.3 will use whichever pair of liblapack.so.3 and libblas.so.3 libraries are currently selected from above.

• libatlas3-base provides liblapack_atlas.so.3 which will always use the ATLAS implementation.