####################################################################
#
# Method(s) to read specific types from the keyboard.
#
# Reading a float number from the keyboard.
#

def read_float(question, minimum=None, maximum=None):
    """Read a float value from the command line"""

    # Validate input as early as possible.
    value = raw_input(question)
    value = float(value)
    # check if the input is within limits
    if minimum is not None and value < minimum:
        print 'ERROR: value = ',value,' smaller than minimum',minimum,'.'
        exit(1)

    if maximum is not None and value > maximum:
        print 'ERROR: value = ',value,' larger than maximum',maximum,'.'
        exit(1)
        
    return value