Converts Lat/Long in decimal to 6 digit Gridsquare

latlongtogrid.rb

def degrees_to_dms(dec)
  deg = dec.floor
  remainder = (dec - deg) * 3600
  min = (remainder/60).floor
  sec = remainder - (min*60)
  
  a = [deg, min, sec]
end


def dec_to_grid(dms)

  grid = ''

  lat = dms[0]+90
  lon = dms[1]+180
  
  v = (lon/20).to_i
  lon -= (v*20)
  grid += (?A + v).chr # first letter
  
  v = (lat/10).to_i
  lat -= (v*10)
  grid += (?A + v).chr # second letter

  p3 = (lon/2).to_i
  grid += p3.to_s # third number
  p4 = (lat).to_i
  grid += p4.to_s # fourth number

  lon -= p3*2
  lat -= p4
  p3 = (?0 + p3).chr
  p4 = (?0 + p4).chr
  p5 = (12 * lon).to_i
  p6 = (24 * lat).to_i
  
  grid += (?a + p5).chr # fifth letter
  grid += (?a + p6).chr # sixth letter

end

def dms_to_degrees(d, m, s)
  degrees = d
  fractional = m / 60 + s / 3600
  if d > 0
    degrees + fractional
  else
    degrees - fractional
  end
end