Function main

Collatz-Conjecture.py:40–86

()

def main():
    # Get the input
    number = input("Enter a number to calculate: ")
    try:
        number = float(number)
    except ValueError:
        print("Error: Could not convert to integer.")
        print("Only numbers (e.g. 42) can be entered as input.")
        main()

    # Prevent any invalid inputs
    if number <= 0:
        print("Error: Numbers zero and below are not calculable.")
        main()
    if number == math.inf:
        print("Error: Infinity is not calculable.")
        main()

    # Confirmation before beginning
    print("Number is:", number)
    input("Press ENTER to begin.")
    print("\nBEGIN COLLATZ SEQUENCE")

    def sequence(number: float) -> float:
        """
        The core part of this program,
        it performs the operations of
        the Collatz sequence to the given
        number (parameter number).
        """
        modulo = number % 2  # The number modulo'd by 2
        if modulo == 0:  # If the result is 0,
            number = number / 2  # divide it by 2
        else:  # Otherwise,
            number = 3 * number + 1  # multiply by 3 and add 1 (3x + 1)
        return number

    # Execute the sequence
    while True:
        number = sequence(number)
        print(round(number))
        if number == 1.0:
            break

    print("END COLLATZ SEQUENCE")
    print("Sequence has reached a 4-2-1 loop.")
    exit(input("\nPress ENTER to exit."))


# Entry point of the program