# Documentation

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# nzmax

Amount of storage allocated for nonzero matrix elements

## Syntax

```n = nzmax(S) ```

## Description

`n = nzmax(S)` returns the amount of storage allocated for nonzero elements in sparse matrix `S`. For sparse matrices, `nzmax(S) >= 1`.

• If `S` is a full matrix, then `nzmax(S)` is equal to `prod(size(S))`.

Often, `nnz(S)` and `nzmax(S)` are the same. But if `S` is created by an operation which produces fill-in matrix elements, such as sparse matrix multiplication or sparse LU factorization, then more storage might 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.