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FreeMat
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Section: Sparse Matrix Support
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);
--> who I
Variable Name Type Flags Size
I double sparse [5000x5000]
--> full(I(1:10,1:10))
ans =
1 0 0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 0 0 0
0 0 1 0 0 0 0 0 0 0
0 0 0 1 0 0 0 0 0 0
0 0 0 0 1 0 0 0 0 0
0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 0 1 0 0
0 0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0 1