Source code for proj

'''
    .. todo::

        Add a modulus_squared function.
'''

import math


def sum_diff(a, b):
    '''
        Calculate the sum and the difference of two variables.

        :param a: number
        :param b: number

        :return sum: sum of *a* and *b*
        :return diff: difference between *a* and *b*

        ::

            # Examples
            sum(1, 3) # output 4, -2
            sum(1+1j, -1j) # output 1, 1+2j
    '''
    sum = a + b
    diff = a - b
    return sum, diff


def modulus(z):
    r'''
        Calculate the modulus :math:`|z|` of a complex number :math:`z`.
        The modulus is given by:

        .. math::

            |z| = \sqrt{[\Re(z)]^2+[\Im(z)]^2}

        :param z: complex number

        :return modulus: modulus of :math:`z`
        
        .. note::
            
            Works for real variables too.
    '''
    modulus = math.sqrt(z.real**2 + z.imag**2)
    return modulus