spDenseSubmat
==============================================

Purpose
----------------
Returns a dense submatrix of a sparse matrix.

Format
----------------
.. function:: y = spDenseSubmat(x, rinds, cinds)

    :param x: data
    :type x: MxN sparse matrix

    :param rinds: row indices.
    :type rinds: Kx1 vector

    :param cinds: column indices.
    :type cinds: Lx1 vector

    :return y: the intersection of *rinds* and *cinds*.

    :rtype y: KxL dense matrix

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

::

    sparse matrix y;
    x = { 0  0  0 10,
          0  2  0  0,
          0  0  0  0,
          5  0  0  0,
          0  0  0  3 };
    
    // Set 'y' to be a sparse matrix with the same values as 'x'
    y = denseToSp(x, 0);
    
    // Extract a submatrix from 'y' with all rows of 'y' and 
    // columns 1, 3 and 4 
    d = spDenseSubmat(y, 0, 1|3|4);

Now *d* is equal to:

::

    0  0 10
    0  0  0
    0  0  0
    5  0  0
    0  0  3

Remarks
-------

If *rinds* or *cinds* are scalar zeros, all rows or columns will be returned.

.. seealso:: Functions :func:`spSubmat`