n = nzmax(S)
n = nzmax(S), where S is a sparse matrix, is the number of storage locations allocated for the nonzero elements in S. For a full matrix, nzmax(A) = prod(size(A)).
Often, nnz(S) and nzmax(S) are the same. But if S has been created by an operation which produces fill-in matrix elements, such as sparse matrix multiplication or sparse LU factorization, more storage may be allocated than is actually required, and nzmax(S) reflects this. Alternatively,
sparse(i,j,s,m,n,nzmax)
or its simpler form, spalloc(m,n,nzmax), can set nzmax in anticipation of later fill-in.
find,issparse,nnz,nonzeros,size,whos
(c) Copyright 1994 by The MathWorks, Inc.