nzmax

Amount of storage allocated for nonzero elements.

Category: Mathematics > Sparse Matrices

Syntax

n = nzmax(S)

Description

A sparse matrix may reserve room for more nonzeros than it holds, so that filling it in later does not require repeated reallocation. nzmax reports that capacity, while nnz reports how much is used. For a full array the answer is simply the number of elements.

Input arguments

S

Sparse or full array.

Output arguments

n

Storage count. It is at least nnz(S) for sparse input and numel(S) for full input.

Example

Capacity versus use

S = sparse([1 2], [1 2], [3 4], 5, 5);
nnz(S)
nzmax(S) >= nnz(S)
nzmax(ones(2, 3))

ans = 2
ans = logical
   1
ans = 6

Notes

The reserved capacity can differ from MATLAB's, for example after spalloc, so compare nzmax against nnz rather than a fixed number.

See also

nnz spalloc sparse nonzeros