Nope, numpy needs libblas and scipy needs libatlas, both of which have to installed from the system package manager. I slap my forehead every time I move to a new system and find that the pip install in the virtualenv failed.

Matplotlib depends on freetype, libpng, and libjpeg as well. Numpy can be built without any external dependencies, but it will be a very slow installation. You're better off with an accelerated BLAS library (e.g. ATLAS/MKL/etc) and some sort of LAPACK library. Some of numpy's functionality also needs a fortran compiler to build. At any rate, there are other system dependencies beyond a basic compiler and the header files for python.