Ruby script to apply Bias-Precession-Nutation to a rectanglar coordinate.

bpn_rotation.rb

#! /usr/local/bin/ruby
# coding: utf-8
#---------------------------------------------------------------------------------
#= バイアス・歳差・章動適用
#
# date          name            version
# 2016.08.27    mk-mode.com     1.00 新規作成
#
# Copyright(C) 2016 mk-mode.com All Rights Reserved.
#---------------------------------------------------------------------------------
#++
require 'eph_bpn'

class BpnRotation
  # ある日のある天体の GCRS 座標（単位: AU）
  COORD = [-1.0020195, 0.0660430, 0.0286337]

  def initialize
    @e = EphBpn.new("20160919")
  end

  def exec
    pos_b  = @e.apply_bias(COORD)       # Apply Bias
    pos_p  = @e.apply_prec(pos_b)       # Apply Precession
    pos_n  = @e.apply_nut(pos_p)        # Apply Nutation
    pos_bp = @e.apply_bias_prec(COORD)  # Apply Bias & Precession
    puts "TDB: #{@e.tdb}"
    puts " JD: #{@e.jd}"
    puts " JC: #{@e.jc}"
    puts "EPS: #{@e.eps}"
    puts "  元の GCRS 座標: #{COORD}"
    puts "  バイアス適用後: #{pos_b}"
    puts "      歳差適用後: #{pos_p}"
    puts "      章動適用後: #{pos_n}"
    puts "* 元の GCRS 座標にバイアス＆歳差同時適用後:"
    puts "                  #{pos_bp})"
  rescue => e
    msg = "[#{e.class}] #{e.message}\n"
    msg << e.backtrace.each { |tr| "\t#{tr}"}.join("\n")
    $stderr.puts msg
    exit 1
  end
end

BpnRotation.new.exec if __FILE__ == $0