ac_generator – Produce an alternating current (AC) input
========================================================

Description
+++++++++++

This device produces an AC input sent by CurrentEvents. The
current is given by

.. math::

        I(t) = \mathrm{offset} + \mathrm{amplitude} \cdot \sin ( \omega t + \phi )

where

.. math::

    \omega  = 2 \pi \cdot \mathrm{frequency} \\
    \phi = \frac{\mathrm{phase}}{180} \cdot \pi

.. include:: ../models/stimulation_device.rst

amplitude
    Amplitude of sine current (pA)

offset
    Constant amplitude offset (pA)

frequency
    Frequency (Hz)

phase
    Phase of sine current (0-360 deg)

Setting `start` and `stop` only windows the current as defined above. It
does not shift the time axis.

See also [1]_.

Set parameters from a stimulation backend
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The parameters in this stimulation device can be updated with input
coming from a stimulation backend. The data structure used for the
update holds one value for each of the parameters mentioned above.
The indexing is as follows:

 0. amplitude
 1. offset
 2. frequency
 3. phase

References
++++++++++

.. [1] Rotter S and Diesmann M (1999). Exact digital simulation of time-
       invariant linear systems with applications to neuronal modeling,
       Biol. Cybern. 81, 381-402. DOI: https://doi.org/10.1007/s004220050570

Sends
+++++

CurrentEvent

See also
++++++++
:doc:`Device <index_device>`, :doc:`Generator <index_generator>`