financial.py 文件源码

def mirr(values, finance_rate, reinvest_rate):
    """
    Modified internal rate of return.

    Parameters
    ----------
    values : array_like
        Cash flows (must contain at least one positive and one negative
        value) or nan is returned.  The first value is considered a sunk
        cost at time zero.
    finance_rate : scalar
        Interest rate paid on the cash flows
    reinvest_rate : scalar
        Interest rate received on the cash flows upon reinvestment

    Returns
    -------
    out : float
        Modified internal rate of return

    """
    values = np.asarray(values, dtype=np.double)
    n = values.size
    pos = values > 0
    neg = values < 0
    if not (pos.any() and neg.any()):
        return np.nan
    numer = np.abs(npv(reinvest_rate, values*pos))
    denom = np.abs(npv(finance_rate, values*neg))
    return (numer/denom)**(1.0/(n - 1))*(1 + reinvest_rate) - 1