tidbits/finance.py at main · LordUbuntu/tidbits · GitHub

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# Made by Jacobus Burger (2022)
# Personal finance functions for the fun of learning


##### PERSONAL FINANCE #####
def simple_interest(P, r, t):
    """
    simple_interest(P, r, t)

    Calculate simple interest over a period
        P = principal
        r = interest rate
        t = number of periods
    """
    return P * r * t


def compound_interest(P, r, n, t):
    """
    compound_interest(P, r, n, t)

    Calculate compunding interest over a period
        P = principal
        r = interest rate
        n = compundings per period
        t = number of periods

    Returns A, the amount accumulated
    """
    return P * (1 + r / n) ** (n * t)


def amortization(P, r, n, t):
    """
    calculate amortization over a period of time.
        P = principal
        r = interest rate
        t = number of periods
        n = payments per period
    """
    return (P * (r / n)) / (1 - (1 + r / n) ** (-n * t))


# total return from mutual funds
def total_return(
    units, cost_per_unit, dividend_per_unit, interest_per_unit, closing_navps
):
    opening = units * cost_per_unit
    dividends = units * dividend_per_unit
    interest = units * interest_per_unit
    closing = units * closing_navps
    return ((closing - opening) + dividends + interest) / opening


# unrealized capital loss/gain over period
def unrealized_capital_loss_or_gain(units, beginning_navps, ending_navps):
    return (units * beginning_navps) - (units * ending_navps)