from numpy import log as ln

def present_amount(A0, p, n):
    return A0 * (1 + p / (360.0 * 100))**n

def initial_amount(A, p, n):
    return A * (1 + p / (360.0*100))**(-n)

def days(A0, A, p):
    return ln(A / A0) / ln(1 + p / (360.0 * 100))

def annual_rate(A0, A, n):
    return 360 * 100 * ((A / A0)**(1.0 / n) - 1)


#What interest rate is needed to double an amount in 10 years?
if __name__ == "__main__":
    A0 = 1; A = 2; n = 10 * 360
    p = annual_rate(A0, A, n)
    print(f'The annual interest rate is {p:.1f}')