Hi, numpy.distutils provides support for Accelerate+veclib on OSX, but does not provide Fortran compiler flags that ensure that the Fortran ABI used is compatible. As a result ASUM, SDOT, (apparently also DDOT), and other common BLAS functions return garbage when called with the wrong ABI. This breaks parts of Scipy. (There's some code to hack around this --- it worked on earlier versions of OSX, but apparently is unreliable on 10.8, demonstrating that this approach is just too brittle.) Moreover, third-party module developers who use Fortran will not be aware of this issue, so it may also break 3rd party code. As far as I see, the options are: 1. Add -ff2c (or whatever is the correct flag for Accelerate) to the Fortran flags on OSX. 2. Drop support for Veclib/Accelerate. I think Accelerate was also incompatible with multiprocessing, which would weigh for option 2. -- Pauli Virtanen