Introduction to Sparse Matrices In Scilab - Projects

PlotSparseReadHBSparsecond2spcondestsprafiterres with precplot the pattern of non nul elements of a sparse matrixread a Harwell-Boeing sparse format filecomputes an approximation of the 2-norm conditionnumber of a s.p.d. sparse matrixestimate the condition number of a sparse matrix(obsolete) iterative refinement for a s.p.d. linear systemcomputes the residual r = Ax-b with precisionFigure 4 – Functions from the umfpack module.( 1, 3) 1.( 2, 4) 1.( 3, 5) 1.( 4, 2) 1.( 5, 1) 1.R =( 5, 5) sparse matrix( 1, 1) 1.4142136( 2, 1) - 0.7071068( 2, 2) 1.2247449( 3, 3) 1.4142136( 4, 3) - 0.7071068( 4, 4) 1.2247449( 5, 2) - 0.8164966( 5, 4) - 0.8164966( 5, 5) 0.8164966According to [8], the spchol function uses two Fortran packages : a sparseCholesky factorization package developed by Esmond Ng and Barry Peytonat ORNL and a multiple minimun-degree ordering package by Joseph Liu atUniversity of Waterloo.5 Functions from the UMFPACK moduleThe UMFPACK module provide several functions related to sparse matrices.These functions are presented in the figure figure 4.In the following script, we read a sparse matrix provided in the Umfpackmodule with the ReadHBSparse function. Then we plot the sparsity patternwith the PlotSparse function.16