.. highlightlang:: us

.. index:: diag

.. _diag:

diag
====

.. us.tag  diag ENGLISH math-create-mat Changed5502

:ref:`diag` creates a diagonal-matrix or a row-vector.

.. function::   r = diag(m)
                r = diag(m, k)

.. us.return

**Return Value**

If *m* is a row- or column-vector, :ref:`diag` creates a matrix. If *m* is a
*nr* * *nc* matrix, :ref:`diag` creates a row-vector with ``min([nr, nc])``
columns.

.. us.params

**Parameters**

.. uparam:: m

   *m* is a real, complex or string vector or matrix.

.. uparam:: k

   *k* is a real scalar and sets the of kth diagonal: k = 0 represents the main
   diagonal, k > 0 above the main diagonal, and k < 0 below the main diagonal.
   Default value is 0.

.. us.example

**Example**

::

   diag([1,2,3])
       1.0000     0.0000     0.0000
       0.0000     2.0000     0.0000
       0.0000     0.0000     3.0000
   [1,2;3,4]
       1.0000     2.0000
       3.0000     4.0000
   diag([1,2;3,4])
       1.0000     4.0000

   diag([1,2,3], 2)
       0.0000     0.0000     1.0000     0.0000     0.0000 
       0.0000     0.0000     0.0000     2.0000     0.0000 
       0.0000     0.0000     0.0000     0.0000     3.0000 
       0.0000     0.0000     0.0000     0.0000     0.0000 
       0.0000     0.0000     0.0000     0.0000     0.0000 

.. us.history

**History**

.. list-table::
   :header-rows: 1

   * - Version
     - Description
   * - R2013.2
     - New parameter *k*.

.. seealso::
   :ref:`overview-mathematic`

:sub:`id-1146555`