spEye
==============================================

Purpose
----------------
Creates a sparse identity matrix.

Format
----------------
.. function:: y = spEye(n)

    :param n: order of identity matrix.
    :type n: scalar

    :return y: sparse identity matrix.

    :rtype y: n x n sparse matrix

Examples
----------------

::

    // Declare 'y' a sparse matrix
    sparse matrix y;

    // Create 3x3 sparse identity matrix
    y = spEye(3);

*y* is now equal to:

::

    1  0  1
    0  1  0
    0  0  1

Remarks
-------

Since sparse matrices are strongly typed in GAUSS, *y* must be defined as
a sparse matrix before the call to :func:`spEye`.

.. seealso:: Functions :func:`spCreate`, :func:`spOnes`, :func:`denseToSp`