LINPACK is a library of MATLAB routines, using single or double precision arithmetic in both real and complex modes, which can solve systems of linear equations for a variety of matrix types and storage modes.
MATLAB already provides a wide set of linear equation solvers. This set of LINPACK routines is provided just for testing and comparison.
LINPACK has officially been superseded by the LAPACK library. The LAPACK library uses more modern algorithms and code structure. However, the LAPACK library can be extraordinarily complex; what is done in a single LINPACK routine may correspond to 10 or 20 utility routines in LAPACK. This is fine if you treat LAPACK as a black box. But if you wish to learn how the algorithm works, or to adapt it, or to convert the code to another language, this is a real drawback. This is one reason I still keep a copy of LINPACK around.
BLAS1 is a library of MATLAB routines for vector operations, used by LINPACK.
LAPACK is a FORTRAN90 library of routines which can solve linear systems of equations or problems involving eigenvalues.
LINPACK is also available in a C++ version and a FORTRAN77 version and a FORTRAN90 version.
LINPACK_C is a version of LINPACK for single precision complex arithmetic.
LINPACK_D is a version of LINPACK for double precision real arithmetic.
LINPACK_S is a version of LINPACK for single precision real arithmetic.
LINPACK_Z is a version of LINPACK for double precision complex arithmetic.
LINPLUS is a library of MATLAB routines similar to LINPACK but covering some other storage formats.
TEMPLATES is a library of MATLAB routines that implement various iterative methods for solving a linear system.
TEST_MAT is a FORTRAN90 collection of test matrices with known inverses, determinants, eigenvalues and so on.
You can go up one level to the MATLAB source codes.