  Stretching is a new sparse matrix method that makes matrices sparser by
making them larger. Stretching has implications for computational complexity
theory and applications in scientific and parallel computing. It changes matrix
sparsity patterns to render linear equations more easily solved by parallel and
sparse techniques. Some stretchings increase matrix condition numbers only
moderately, and thus solve linear equations stably. For example, these
stretchings solve arrow equations with accuracy and expense preferable to other
solution methods.
