def equation_of_time_pvcdrom(dayofyear):
<EOL>bday =_calculate_simple_day_angle(dayofyear) - (<NUM_LIT> * np.pi / <NUM_LIT>) * <NUM_LIT><EOL>return <NUM_LIT> * np.sin(<NUM_LIT> * bday) - <NUM_LIT> * np.cos(bday) - <NUM_LIT> * np.sin(bday)<EOL>
Equation of time from PVCDROM.

`PVCDROM`_ is a website by Solar Power Lab at Arizona State
University (ASU)

.. _PVCDROM: http://www.pveducation.org/pvcdrom/2-properties-sunlight/solar-time

Parameters
----------
dayofyear : numeric

Returns
-------
equation_of_time : numeric
    Difference in time between solar time and mean solar time in minutes.

References
----------
[1] Soteris A. Kalogirou, "Solar Energy Engineering Processes and
Systems, 2nd Edition" Elselvier/Academic Press (2009).

See Also
--------
equation_of_time_Spencer71