On 10 August 2013 13:43, Roy Smith <r...@panix.com> wrote: > > In article <mailman.425.1376137459.1251.python-l...@python.org>, > Oscar Benjamin <oscar.j.benja...@gmail.com> wrote: > >> You should use apt-get for numpy/scipy on Ubuntu. Although >> unfortunately IIRC this doesn't work as well as it should since Ubuntu >> doesn't install the appropriate BLAS/LAPACK libraries by default >> (leaving you with numpy's fallback libraries). > > That really kind of proves my point. It's *not* easy to install. > Theres' a choice of methods, some of which work in some environments, > some of which work in others. And even if apt-get is the preferred > install method on Ubuntu, it's a method which is unavailable to people > without root access (and may be undesirable if you rely on virtualenv to > keep multiple projects cleanly separated). > > And, what happens if you don't have the right libraries? Do you end up > with an install which is missing some functionality, or one where all > the calls work, but they're slower, or numerically unstable, or what?
AFAIK not having separate BLAS/LAPACK libraries just means that certain operations are a lot slower. If there are differences in accuracy then they aren't significant enough that I've noticed. I think that the reason Ubuntu doesn't install them by default is because it's not sure which ones you want to use. Possibly the best free setup comes from using ATLAS but this is optimised in a CPU-specific way at build time. Ubuntu doesn't provide binaries for it as using generic x86 executables would defeat much of the point of the library (they do make it a lot easier by providing a source package though). Oscar -- http://mail.python.org/mailman/listinfo/python-list
