'''
// C: 0  .c.. 100 [100]
// F: 32 .f.. 212 [180]
// (f-32)/(c-0) = 180/100
// c = (f-32) * 100/180
// f = c * 180/100 + 32
'''
def toCelsius(f):
  return (f-32) * 5/9		# (5/9) may be evaluated to 0 in Python 2

def toFahrenheit(c):
  return c * 180/100 + 32

# Challenge: re-write the above functions into lambda functions ...

if __name__ == "__main__":

  print(77, 'degree F = ', toCelsius(77), 'degree C')
  print("")

  print(25, 'degree C = ', toFahrenheit(25), 'degree F')
  print("")
  
  print('round-trip conversion for F=77 produces F=', toFahrenheit( toCelsius(77) ))
  print('round-trip conversion for C=25 produces C=', toCelsius( toFahrenheit(25) ))
  print("")
  
  # Every 10 (5) deg C change makes 18 (9) deg F change
  print('deltaC==10 <=> deltaF==18')
  for c in range(0,100+1,10):
    print('%3d degree C = %5.1f degree F' % (c, toFahrenheit(c)))
  print("")
  
  print('deltaF==9 <=> deltaC==5')
  # Every 18 (9) deg F change makes 10 (5) deg C change
  for f in range(32,212+1,9):
    print('%3d degree F = %5.1f degree C' % (f, toCelsius(f)))
  print("")