1. Emerge python with USE="threads". 2. Emerge sci-libs/atlas without threads (the default). 3. Emerge dev-python/numpy - no problem here. 4. Open a python console and type: >>> import numpy Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.7/site-packages/numpy/__init__.py", line 137, in <module> import add_newdocs File "/usr/lib/python2.7/site-packages/numpy/add_newdocs.py", line 9, in <module> from numpy.lib import add_newdoc File "/usr/lib/python2.7/site-packages/numpy/lib/__init__.py", line 13, in <module> from polynomial import * File "/usr/lib/python2.7/site-packages/numpy/lib/polynomial.py", line 17, in <module> from numpy.linalg import eigvals, lstsq File "/usr/lib/python2.7/site-packages/numpy/linalg/__init__.py", line 48, in <module> from linalg import * File "/usr/lib/python2.7/site-packages/numpy/linalg/linalg.py", line 23, in <module> from numpy.linalg import lapack_lite ImportError: /usr/lib/libatlas.so.3: undefined symbol: ATL_DecAtomicCount 5. Also sci-libs/scipy fails to emerge. -------------------------------------------------------------------------------------- Solution set atlas USE="threads", rebuild atlas and problem solved. I suggest that if python has USE="threads" then the numpy ebuild should require an atlas with USE="threads" also. (perhaps through virtual/cblas). Note. The above were done with: dev-lang/python-2.7.3 sci-libs/atlas-3.9.71 dev-python/numpy-1.6.1-r1 but I think versions are immaterial.
This is unreproducable here with atlas-3.10.0, numpxy-1.6.2 and python-2.7.3-r2. Please test again.