Running iDEA
============

As it is a python package there are many different ways of running iDEA.

Using the iDEA code directly
----------------------------
Use `idea-run` to produce the default parameters file: 

.. code-block:: bash

    idea-run

In order not to overwrite results from different calculations,
make sure to choose different run names for different inputs

.. literalinclude:: /../iDEA/parameters.py
    :lines: 1-20
    :emphasize-lines: 9

Using the iDEA package in a python script
-----------------------------------------
Since iDEA is designed as a python package, it can be run from
everywhere, if you let your python installation know where the package is located.
During the installation of iDEA the `idea-public` directory should have been
added to PYTHONPATH. To test this has worked simply perform the following

.. code-block:: bash

    cd $test_folder                  # some folder you have created
    cp $path_to_iDEA/iDEA/parameters.py . # where you have downloaded iDEA
    idea-run

Here, we are running iDEA much in the same way as before but your
:code:`$test_folder` can be located anywhere on your computer.

The main advantage of having an iDEA python package is that you can access its
functionality directly in a python script.

The example below uses a python loop to converge the grid spacing for an iDEA
calculation of a test system of non-interacting electrons in a harmonic well.

.. code-block:: python

    from iDEA.input import Input
    
    # read parameters file
    inp = Input.from_python_file('parameters.py')
    inp.run.verbosity = 'low'
    
    # Converging xmax parameter
    for xmax in [4,6,8,10]:
        # Note: the dependent sys.deltax is automatically updated
        inp.sys.xmax = xmax
    
        # perform checks on input parameters
        inp.check()
        inp.execute()
        E = inp.results.non.gs_non_E
        print(" xmax = {:4.1f}, E = {:6.4f} Ha".format(xmax,E))

In order to run this example, save it to a file ``run.py`` and do

.. code-block:: bash

    python run.py


Using the iDEA package in an ipython shell
------------------------------------------
As iDEA is a python package it can also be run from the interactive python shell
(:code:`ipython`). This is particularly useful as ipython has a convenient auto-complete
feature. The following example can be run in an ipython shell line-by-line.

.. code-block:: python

    from iDEA.input import Input

    # import parameters file
    pm = Input.from_python_file('parameters.py')

    # change parameters
    pm.run.EXT = True
    pm.run.NON = True
    print(pm.run)

    # run jobs
    results = pm.execute()

    # plot the relevant results
    x = pm.space.grid
    plt.plot(x, results.ext.gs_ext_den, label='exact')
    plt.plot(x, results.non.gs_non_den, label='non-interacting')
    plt.legend()
    plt.show()