Module: Holidays::Definition::CustomMethods::CN

Defined in:
lib/holidays/definition/custom_methods/cn.rb

Overview

cn custom holiday calculations, ported verbatim from the methods: block in definitions/cn.yaml.

Class Method Summary collapse

Class Method Details

.cn_qingming(year) ⇒ Object

Qingming falls when the sun reaches celestial longitude 15 degrees, which lands on 4 or 5 April. This is the standard solar-term approximation; the century constant shifts between the 20th and 21st centuries.



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# File 'lib/holidays/definition/custom_methods/cn.rb', line 14

def cn_qingming(year)
  constant =
    case year
    when 1900..1999
      5.59
    when 2000..2099
      4.81
    else
      raise IndexError.new("Out of range")
    end
  y = year % 100
  Date.civil(year, 4, (y * 0.2422 + constant).floor - (y / 4))
end