[SciPy-User] Numpy / Scipy build / test errors on Mac OS X Lion with Macports

[Robert Kern]

On Wed, Nov 23, 2011 at 14:15, Christoph Deil
<deil.christoph at googlemail.com> wrote:
> Hi,
>
> I would like to use numpy / scipy git master on Mac OS X Lion with XCode 4.2.
>
> The recommendation at http://www.scipy.org/Installing_SciPy/Mac_OS_X is to use the official Python distribution, but I already have a ton of other libraries and python packages (e.g. ipython 0.11 with working qtconsole) installed with the Macports python, and I guess it is not possible to mix packages installed with the Macports / official python?

Probably not.

> Would it be helpful if I file tickets with the build and test logs for numpy and scipy using the XCode and Macports compilers, or are these problems well-known and simply too hard to fix?

I don't know what problems you are referring to, so yes, reporting
them would help.

> I frequently had build problems with numpy / scipy also on other machines and would like to understand the issues better.
> E.g. does numpy need a Fortran compiler or is it all C/C++?

numpy is all C. The only time you need a Fortran compiler to build
numpy is if you link against Fortran-compiled BLAS/LAPACK libraries.
scipy does have Fortran code that it needs to compile.

> Why are there often problems with gfortran versions/builds other than http://r.research.att.com/gfortran-lion-5666-3.pkg? Is the problem that the fortran compilers or the numpy / scipy libraries are non-standard-complient?

The "problem", such as it is, is that Apple extended gcc to add
several flags for handling its multiple -arch flags and for
implementing OS X's special brand of dynamic linking, both of which
are necessary to build Python extensions for framework builds of
Python on OS X. However, Apple does not provide similarly extended
builds of gfortran. They leave that to third parties. The R group that
makes the gfortran binaries at http://r.research.att.com have
consistently made good builds of gfortran that provide these flags.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco