cg, a FORTRAN90 code which implements a simple version of the conjugate gradient (CG) method for solving a system of linear equations of the form A*x=b, suitable for situations in which the matrix A is positive definite (only real, positive eigenvalues) and symmetric.
The computer code and data files made available on this web page are distributed under the GNU LGPL license.
cg is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.
CG_RC, a FORTRAN90 code which implements the conjugate gradient method for solving a positive definite sparse linear system A*x=b, using reverse communication.
FEM2D_POISSON_CG, a FORTRAN90 code which solves Poisson's equation on a triangulated region, using the finite element method (FEM), sparse storage, and a conjugate gradient solver.
SPARSE_DISPLAY, a FORTRAN90 code which can read information defining a matrix of numbers and display the sparsity pattern or location of the nonzero elements using gnuplot. This operation is already available in the built-in MATLAB "spy" command.
WATHEN, a FORTRAN90 code which compares storage schemes (full, banded, sparse triplet) and solution strategies (Linpack full, Linpack banded, conjugate gradient) for linear systems involving the Wathen matrix, which can arise when solving a problem using the finite element method (FEM).