PUNC (Portable Understructure for Numerical Computing) is a small standard collection of software libraries for numerical computing. The PUNC collection includes reference implementations of the standard (dense matrix) linear algebra tools BLAS and LAPACK, and also includes some newer (sparse matrix) linear algebra tools ARPACK, SuperLU, CgCode, and PMG. PUNC also provides some additional basic infrastructure such as the standard F2C header and corresponding library (libF2C), to support the use of F2C'd FORTRAN codes, and some other standard tools used to build numerical simulation software, such as the HDF5 library. While most of the libraries included in PUNC are completely stand-alone, and are the reference implementations developed by the individual library authors, PUNC also provides some Object-oriented C wrappers (written by the FETK developers) for use with Object-oriented C/C++ codes such as FETK . This is accomplished by building PUNC on top of FETK 's MALOC library.