Перевести код с Ruby на PHP

#!/usr/bin/ruby
 
=begin
Equation of Time calculation
    *** No guarantees are implied. Use at your own risk ***
 
    Written by E. Sevastyanov, 2017-05-14
 
    Based on "Equation of time" WikiPedia article as of 2016-11-28
    (which describes angles in a bewildering mixture of degrees and radians)
    and
    Del Smith, 2016-11-29
 
    It appears to give a good result, but I make no claims for accuracy.
=end
 
pi = (Math::PI) # pi
delta = (Time.now.getutc.yday - 1) # (Текущий день года - 1)
 
yy = Time.now.getutc.year
np = case yy #The number np is the number of days from 1 January to the date of the Earth's perihelion. (http://www.astropixels.com/ephemeris/perap2001.html)
when 2017 ; 3
when 2018 ; 2
when 2019 ; 2
when 2020 ; 4
when 2021 ; 1
when 2022 ; 3
when 2023 ; 3
when 2024 ; 2
when 2025 ; 3
when 2026 ; 2
when 2027 ; 2
when 2028 ; 4
when 2029 ; 1
when 2030 ; 2 
else; 2
end 
 
a = Time.now.getutc.to_a; delta = delta + a[2].to_f / 24 + a[1].to_f / 60 / 24 # Поправка на дробную часть дня
 
lambda = 23.4406 * pi / 180; # Earth's inclination in radians
omega = 2 * pi / 365.2564 # angular velocity of annual revolution (radians/day)
alpha = omega * ((delta + 10) % 365) # angle in (mean) circular orbit, solar year starts 21. Dec
beta = alpha + 0.03340560188317 * Math.sin(omega * ((delta - np) % 365)) # angle in elliptical orbit, from perigee  (radians)
gamma = (alpha - Math.atan(Math.tan(beta) / Math.cos(lambda))) / pi # angular correction
eot = (43200 * (gamma - gamma.round)) # equation of time in seconds
puts "EOT =" + (-1 * eot).to_s + " секунд"