gistfile1.txt

def decimal_to_roman(num):
    """
    Convert a decimal number to Roman numerals.
    
    Args:
        num: Integer between 1 and 3999
        
    Returns:
        String representing the Roman numeral
    """
    if not isinstance(num, int) or num < 1 or num > 3999:
        raise ValueError("Number must be an integer between 1 and 3999")
    
    # Mapping of values to Roman numerals in descending order
    values = [
        (1000, 'M'),
        (900, 'CM'),
        (500, 'D'),
        (400, 'CD'),
        (100, 'C'),
        (90, 'XC'),
        (50, 'L'),
        (40, 'XL'),
        (10, 'X'),
        (9, 'IX'),
        (5, 'V'),
        (4, 'IV'),
        (1, 'I')
    ]
    
    result = ""
    
    for value, numeral in values:
        count = num // value
        if count:
            result += numeral * count
            num -= value * count
    
    return result