An interactive graphic tool to plot the structure of large sparse matrices

Many engineering and scientific problems involve the solution of large sparse linear systems. To determine an optimal solving strategy for such systems, it is essential to understand the largeand small-scale properties of the associated sparse matrices. We present a graphic tool to analyze the sparsity pattern and the numeric structure of these matrices. Through examples, drawn from our practical experience, we demonstrate the effectiveness and the interactive features of the tool. These features include zooming, scrolling in different directions, sorting of rows and/or columns, and selective plotting, according to the values of the matrix coefficients.