Source code for irfpy.vels.bible.kfactor

''' Implementation of K-factor.  Section 4 of :ref:`vexelsbible`.

This is an energy-averaged k-factor.
'''

import numpy as np

def kfactors():
    ''' Return the list of k-factor.

    It refers to Table 1 in the bible.

    :returns: The k-factors of the specified anode in eV/V
    :rtype: ``nparray``
    '''

    return np.array([10.490, 10.627, 10.824, 10.956, 11.077,
        11.192, 11.310, 11.397, 11.315, 11.193,
        11.007, 11.808, 10.558, 10.419, 10.355,
        10.363])


def fit_kfactor():
    ''' Return the function of the k-factor.

    It refers to the equation (1) in bible.

    :returns: Function of k-factor.  The function will take 1 argument specifying anode.

    >>> func_kfactor = fit_kfactor()  # Return the function of k-factor
    >>> k10 = func_kfactor(10)  # Return the k-factor of anode 10.
    >>> print('%.3f' % k10)
    11.012
    '''
    func = lambda x: (((0.000323 * x - 0.00889) * x + 0.0573) * x + 0.0424 ) * x + 10.518
    return func


def kfactor(anode, src="table"):
    ''' Return the k-factor of the specified anode.

    :param anode: The number of anode.
    :keyword src: The source, ``"table"`` or ``"fit"``. ``"table"`` refers to :func:`kfactor` and ``"fit"`` referes to :func:`fit_kfactor`.

    >>> print(kfactor(5))
    11.192
    >>> print("%.3f" % kfactor(5, src="fit"))
    11.253
    '''
    if src == "table":
        return kfactors()[anode]
    elif src == "fit":
        return (fit_kfactor())(anode)

    else:
        raise ValueError("Unknown source for kfactor")


import unittest,doctest
def doctests():
    return unittest.TestSuite((
        doctest.DocTestSuite(),
        ))
if __name__=='__main__':
        unittest.main(defaultTest='doctests')