sparse_display, a MATLAB 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.
The user can call "spy_ge" and pass in a matrix, in general (GE) format; the routine will then locate the nonzero entries, and write out a data file and a command file which together can be used to instruct gnuplot to create a sparsity plot.
If the user already has a file containing a list of pairs of indices (I,J) corresponding to nonzero matrix entries, then the user can call "spy_file", which will write out a command file only. Together, the user data file and the command file can be used to instruct gnuplot to create a sparsity plot.
The computer code and data files made available on this web page are distributed under the GNU LGPL license.
sparse_display is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.
cg, a MATLAB 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.
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