.. highlightlang:: us

.. index:: atan

.. _atan:

atan
====

.. us.tag  atan ENGLISH math-trigo

:ref:`atan` calculates the arctangent.

.. function::  r = atan(m)

.. us.return

**Return Value**

*r* is the arctangent of *m*.

.. us.params

**Parameters**

.. uparam:: m

   *m* is a real or complex matrix.

.. us.comment

**Comment**

Algorithm: ``(1 ./ 2i) .* log((1 + 1i .* x) ./ (1 - 1i .* x))``.

.. us.example

**Example**

::

   * printf("%.17f\n", atan(1)*4);
   3.14159265358979310

.. seealso::
   :ref:`overview-mathematic`,
   :ref:`atan2`,
   :ref:`tan`

:sub:`id-1320956`