k = issparse(X)
issparse(X) returns 1 if the storage class of X is sparse and 0 otherwise. Since most of MATLAB's functions work correctly and efficiently with both sparse and full matrices, issparse(X) is not needed very often.
if issparse(X)nrm = normest(X);elsenrm = norm(X);end
full,sparse
(c) Copyright 1994 by The MathWorks, Inc.