.. _example IPython:

Example: IPython
----------------

The basics of this file are as in :ref:`Example: Demag field in uniformly
magnetised sphere <example 1>`: a ferromagnetic sphere is studied, and initially
configured to have homogeneous magnetisation. 

Here is the source code of :download:`sphere_ipython.py
</example_ipython/sphere_ipython.py>`

.. include:: sphere_ipython.py
  :literal:

To execute this script, we have to give its name to the :ref:`nsim`
executable, for example (on linux)::

  $ nsim sphere_ipython.py

The new command appearing here is:: 

  nmag.ipython()

This calls an interactive python interpreter (this is like the
standard ``ipython`` interpreter called from the command prompt).

Once we are "inside" this ipython interpreter, we can interactively work with
the simulation object. We demonstrate this with the transcript of such
a session::

  $ nsim sphere_ipython.py

  <snip>

  In [1]: sim.get_subfield("H_demag")
  Out[1]:
  array([[ -3.30028671e+05,  -2.57073101e+01,  -4.63461085e+01],
         [ -3.30518650e+05,  -2.65364907e+01,   2.12323921e+02],
         [ -3.30380750e+05,  -1.34382835e+02,   1.94635283e+01],
         ...,
         [ -3.30063839e+05,   4.56312711e+01,  -1.31204248e+02],
         [ -3.30056243e+05,  -3.23341645e+01,  -2.26732582e+02],
         [ -3.29950815e+05,   4.44150291e+01,  -5.41700794e+01]])
  
  In [2]: sim.set_m([0,0,1])
  
  In [3]: sim.get_subfield("H_demag")
  Out[3]: 
  array([[ -6.86773473e+01,   4.44496808e+01,  -3.30084368e+05],
         [ -2.83792944e+02,   1.78935681e+02,  -3.30268314e+05],
         [ -2.04396266e+02,   2.48374212e+02,  -3.30180923e+05],
         ..., 
         [ -1.02055030e+02,  -9.53215211e+01,  -3.30239401e+05],
         [  1.94875407e+02,   1.22757584e+02,  -3.29771010e+05],
         [  6.16259262e+01,   1.66071597e+02,  -3.29848851e+05]])

Note that within ipython, one can just press the TAB key to
autocomplete object names, functions and commands.

You can leave the ipython environment by pressing CTRL+D. For the
script shown here, this will print ``Back in main code`` before the
end of the script is reached. The ``ipython()`` command is
occasionally a handy debugging feature: in order to investigate the
behaviour of the system "on the spot", one can insert an ``ipython`` call
into the script which will open an interactive command line.