FreeMat: SPEYE Sparse Identity Matrix

FreeMat

- Main Page
- Related Pages

SPEYE Sparse Identity Matrix

Section: Sparse Matrix Support

# Usage

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.

# Example

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