# temperature.py
# Walker M. White (wmw2)
# September 6, 2012
"""Conversion functions between fahrentheit and centrigrade

This module shows off two functions for converting temperature
back and forth between fahrenheit and centigrade.  It also
shows how to use variables to represent "constants", or values
that we give a name in order to remember them better.

This module has been extended from the version in the previous
lecture to include script code that unit tests the functions."""
import cornelltest

# Functions

def to_centigrade(x):
    """Returns: x converted to centigrade

    Value returned has type float.

    Precondition: x is a float measuring temperature in fahrenheit"""
    return 5*(x-32)/9.0

def to_fahrenheit(x):
    """Returns: x converted to fahrenheit

    Value returned has type float.

    Precondition: x is a float measuring temperature in centigrade"""
    return 9*x/5.0+32

# Constants

FREEZING_C = 0.0   # Temperature water freezes in centrigrade

FREEZING_F = to_fahrenheit(FREEZING_C)

BOILING_C = 100.0  # Temperature water freezes in centrigrade

BOILING_F = to_fahrenheit(BOILING_C)