utils.py 文件源码

def float_to_decimal(f):
    """
    Convert a floating point number to a Decimal with
    no loss of information. Intended for Python 2.6 where
    casting float to Decimal does not work.
    """
    n, d = f.as_integer_ratio()
    numerator, denominator = Decimal(n), Decimal(d)
    ctx = Context(prec=60)
    result = ctx.divide(numerator, denominator)
    while ctx.flags[Inexact]:
        ctx.flags[Inexact] = False
        ctx.prec *= 2
        result = ctx.divide(numerator, denominator)
    return result