Creates a sparse identity matrix of the given size. The syntax for its use is
y = speye(m,n)
which forms an m x n
sparse matrix with ones on the main diagonal,
or
y = speye(n)
which forms an n x n
sparse matrix with ones on the main diagonal. The
matrix type is a float
single precision matrix.
The following creates a 5000 by 5000 identity matrix, which would be
difficult to do using sparse(eye(5000))
because of the large amount
of intermediate storage required.
--> I = speye(5000) I = <float> - size: [5000 5000] Matrix is sparse with 5000 nonzeros --> full(I(1:10,1:10)) ans = <float> - size: [10 10] Columns 1 to 3 1.0000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 Columns 4 to 6 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 Columns 7 to 9 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 1.0000000 0.00000000 0.00000000 0.00000000 Columns 10 to 10 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 1.0000000