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Sparse identity matrix


S = speye(m,n)
S = speye([m n])
S = speye(n)
S = speye


S = speye(m,n) and S = speye([m n]) form an m-by-n sparse matrix with 1s on the main diagonal.

S = speye(n) abbreviates speye(n,n).

S = speye returns the sparse form of the 1-by-1 identity matrix.


I = speye(1000) forms the sparse representation of the 1000-by-1000 identity matrix, which requires only about 16 kilobytes of storage. This is the same final result as I = sparse(eye(1000,1000)), but the latter requires eight megabytes for temporary storage for the full representation.

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