The ATLAS (Automatically Tuned Linear Algebra Software) project is
an ongoing research effort focusing on applying empirical techniques
in order to provide portable performance. 

At present, it provides C and Fortran77 interfaces to a
portably efficient BLAS implementation, as well as a few routines from LAPACK.

If you use blas, you can simply change flags when linking,
from -lblas to -lf77blas -latlas (order is important).

A few routines from LAPACK are merged into one library as libalapack.
It requres both C and Fortran77 interfaces, and thus that link line would be:
-lalapack -lf77blas -lcblas -latlas -lg2c -lm .

Other choice of CC and CFLAGS are *NOT* recommended.
They are already optimized for this platform and automatically searched.

WWW: http://math-atlas.sourceforge.net/