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Allocate space for sparse matrix


S = spalloc(m,n,nz)


S = spalloc(m,n,nz) creates an all zero sparse matrix S of size m-by-n with room to hold nz nonzeros, where nz >= 1. The matrix can then be generated column by column without requiring repeated storage allocation as the number of nonzeros grows.

spalloc(m,n,nz) is shorthand for



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

S = spalloc(n,n,3*n);
for j = 1:n
    S(:,j) = [zeros(n-3,1)' round(rand(3,1))']';

See Also

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Introduced before R2006a

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