Function _log10_lb

Lib/_pydecimal.py:5980–5987

Compute a lower bound for 100*log10(c) for a positive integer c.

(c, correction = {
        '1': 100, '2': 70, '3': 53, '4': 40, '5': 31,
        '6': 23, '7': 16, '8': 10, '9': 5})

    return coeff, exp

def _log10_lb(c, correction = {
        '1': 100, '2': 70, '3': 53, '4': 40, '5': 31,
        '6': 23, '7': 16, '8': 10, '9': 5}):
    """Compute a lower bound for 100*log10(c) for a positive integer c."""
    if c <= 0:
        raise ValueError("The argument to _log10_lb should be nonnegative.")
    str_c = str(c)
    return 100*len(str_c) - correction[str_c[0]]

##### Helper Functions ####################################################