MGMRES is a FORTRAN77 library which applies a simple restarted GMRES iteration to a sparse linear system stored in a simple format, by Lili Ju.
One matrix format used is the DSP or ST or "sparse triplet" format, which simply stores NZ_NUM, the number of nonzeros, and stores the K-th nonzero matrix entry as
Another matrix format used is the CR or "sparse compressed row" format, which is similar to the sparse triplet format except that it the vector of row indices is compressed to a vector of length N+1 which points to the beginning of the set of entries for each row.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
MGMRES is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.
CG_RC, a FORTRAN77 library which implements the conjugate gradient method for solving a positive definite sparse linear system A*x=b, using reverse communication.
DSP, a data directory which contains examples of DSP files, a sparse matrix file format, storing just (I,J,A(I,J)), and using one-based indexing.
HB, a data directory which contains examples of HB files, the Harwell Boeing sparse matrix file format;
HB_TO_ST, a FORTRAN77 program which converts a sparse matrix from Harwell-Boeing to sparse triplet format.
SPARSEKIT, a FORTRAN77 library which implements operations on sparse matrices, including conversion between various formats, by Yousef Saad.
SPARSEPAK, a FORTRAN77 library which forms an obsolete version of the Waterloo Sparse Matrix Package.
ST, a data directory which contains examples of ST files, the Sparse Triplet format, a sparse matrix file format, storing just (I,J,A(I,J)), and using zero-based indexing.
UMFPACK, a FORTRAN77 library which solves unsymmetric sparse linear systems, by Timothy Davis, Iain Duff.
Original C version by Lili Ju, Mathematics Department, University of South Carolina; FORTRAN77 version by John Burkardt.
You can go up one level to the FORTRAN77 source codes.