s = nonzeros(X)
s = nonzeros(X) is a full column vector of the nonzero elements in X, ordered by columns.
This gives the s, but not the i and j, from [i,j,s] = find(X). Generally,
length(s) = nnz(X) <= nzmax(X) <= prod(size(X))
find,issparse,nnz,nzmax,size,whos
(c) Copyright 1994 by The MathWorks, Inc.