# spalloc

## Purpose

Allocate space for sparse matrices.

## Synopsis

    S = spalloc(m,n,nzmax)

## Description

`S = spalloc(m,n,nzmax)` creates an all zero sparse matrix `S` of size `m`-by-`n` with room to hold `nzmax` nonzeros. The matrix can then be generated column by column without requiring repeated storage allocation as the number of nonzeros grows.

`spalloc(m,n,nzmax)` is shorthand for

    sparse([],[],[],m,n,nzmax)

## Examples

To efficiently generate a sparse matrix which has an average of at most three nonzero elements per column

    S = spalloc(n,n,3*n);
    for j = 1:n
        S(:,j) = { the j-th column }
    end

(c) Copyright 1994 by The MathWorks, Inc.