Exploiting MATLAB's Data Structures

Sparse Matrices

Usage: Use sparse matrices when the essential data include lots of zeros.

Examples:

histogram of indexed images

connection matrices such as those for finite elements

binary trees

Problem #4 - Sparse Matrices

More info ...

Specialized sparse functions

sparse	Create sparse array
spy	Visualize sparsity pattern
full	Convert to full array
find	Find indices of non-zero elements
nnz	number of non-zeros

• Given the location of the non-zero elements (i,j) and their value v, the sparse command can create a sparse matrix with this structure via s = sparse(i,j,v).
• [i,j,v] = find(s) returns those same values from the sparse matrix.

Copyright © 1997 The MathWorks, Inc.
clay@mathworks.com
$Revision$ $Date$