Got it! *Summary:* * Installing a numpy wheel (e.g. `pip install numpy==1.21.0`) uses its embedded OpenBLAS on every platform that has a wheel. That OpenBLAS is always compiled with gcc/gfortran. In this case, `np.show_config()` reports `library_dirs = ['/usr/local/lib']` even though there's no libblas in that directory.
* Installing numpy from source (e.g. `pip install numpy==1.21.0 --no-binary numpy)` looks for BLAS & LAPACK libraries at build time as influenced by the environment vars NPY_BLAS_ORDER/NPY_LAPACK_ORDER or by the file ~/.numpy-site.cfg. On macOS, 'accelerate' is in the default search order after 'openblas'. On macOS < 11.3, importing numpy that's linked to Accelerate will detect an Accelerate bug and raise a RuntimeError. On Wed, Jul 7, 2021 at 1:32 PM Ralf Gommers <ralf.gomm...@gmail.com> wrote: > > > On Wed, Jul 7, 2021 at 9:56 PM Jerry Morrison < > jerry.morrison+nu...@gmail.com> wrote: > >> Would someone please answer installation questions about NumPy's BLAS on >> macOS? I'm not finding the answers in the release notes >> <https://github.com/numpy/numpy/releases>, the PR >> <https://github.com/numpy/numpy/pull/18874> source, the docs >> <https://numpy.org/doc/1.21/>, or Stack Overflow >> <https://stackoverflow.com/search?tab=newest&q=%5bnumpy%5d%20openblas>. >> >> >> Q1. The NumPy 1.21.0 release note >> <https://github.com/numpy/numpy/releases/tag/v1.21.0> says "This change >> enables the Accelerate Framework as an option on macOS." How to set >> that option on/off? >> > > It's autodetected at build time. If you have no other BLAS installed, it > will be used. Or explicitly select it with NPY_BLAS_ORDER/NPY_LAPACK_ORDER > > >> Q2. How to determine if NumPy uses Accelerate vs. its internal copy of >> OpenBLAS? >> After installing a wheel, `numpy.show_config()` shows the openblas_info >> library_dirs et al as '/usr/local/lib'. Neither '/usr/local/lib/' nor >> 'site-packages/numpy/' contains a *blas*.so library (for Python 3.8.* on >> macOS 10.14.6) but the doc <https://numpy.org/install/> says "The >> OpenBLAS libraries are included in the wheel." >> > > It's a build-time option, you cannot select it at runtime. > > >> Q3. How to pip install NumPy 1.21.0 in a way that ensures it uses its >> embedded OpenBLAS on macOS as on Linux? I'm aiming for as portable results >> as possible. Or should we link NumPy to an external OpenBLAS via `pip >> install numpy --no-binary numpy==1.21.0` with `~/.numpy-site.cfg`? (Ditto >> for SciPy.) >> > > If you install a wheel, you will always get the bundled OpenBLAS on every > platform for which we have binary wheels. > > >> >> Q4. Can the new NPY_* environment variables select specific BLAS & LAPACK >> libraries through pip install, and perhaps install faster than building >> NumPy, SciPy, etc. from source? How to do that? >> > > This question seems a little bit confused. Those env vars just select the > BLAS/LAPACK library. It will not affect build time - we're never building > BLAS or LAPACK itself from source. > > >> Q5. Is NumPy's embedded OpenBLAS compiled by gcc or clang? Is that >> controllable via `pip install`? >> > > gcc/gfortran. and no, you cannot control it through pip > > Cheers, > Ralf > > >> Thank you! >> _______________________________________________ >> NumPy-Discussion mailing list >> NumPy-Discussion@python.org >> https://mail.python.org/mailman/listinfo/numpy-discussion >> > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@python.org > https://mail.python.org/mailman/listinfo/numpy-discussion >
_______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@python.org https://mail.python.org/mailman/listinfo/numpy-discussion
