.. highlightlang:: us

.. index:: acos

.. _acos:

acos
====

.. us.tag  acos ENGLISH math-trigo

:ref:`acosh` calculates the arccosine.

.. function::  r = acos(m)

.. us.return

**Return Value**

*r* is the arccosine of the matrix *m*.

.. us.params

**Parameters**

.. uparam:: m

   *m* is a real or complex matrix.

.. us.comment

**Comment**

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

.. seealso::
   :ref:`overview-mathematic`,
   :ref:`cos`,
   :ref:`acosh`

:sub:`id-1076924`