学生卡在一个特定的方程求解问题上

Question

我必须使用复利方程算出我的输入之一增加三倍所花费的时间。用户必须输入预期的年度 return 和初始股价，并且代码应该吐出初始股价翻三倍所需的年数（四舍五入为整数）。但是，使用我编写的代码，它什么也没有给我，我不知道该怎么做。

我的代码：

from sympy.solvers import solve
from sympy import Symbol


x = Symbol('x')
Stock_Ticker = input("Enter the stock ticker: ")
EAR = float(input("Enter Expected Annual Return: "))
ISP = float(input("Enter initial stock price: "))

expr = ISP * (1+EAR)**x

solve(ISP *(1+EAR)**x,x)

sol = solve(ISP *(1+EAR)**x,x)

print ("The price of", Stock_Ticker, "tripled after", sol, "years")

我的输出是：

The price of (Stock_Ticker) tripled after [] years

Answer 1

问题

表达式 sol = solve(ISP *(1+EAR)**x,x) 永远不会变为零。
您希望 sol = solve(ISP *(1+EAR)**x,x) - 3*ISP 在值变为 3*ISP

代码

from sympy.solvers import solve
from sympy import Symbol

x = Symbol('x')
Stock_Ticker = input("Enter the stock ticker: ")
EAR = float(input("Enter Expected Annual Return: "))
ISP = float(input("Enter initial stock price: "))

expr = ISP * (1+EAR)**x - 3*ISP   # subtract 3*initial price since we want to find when expression becomes zero

sol = solve(expr, x)              # Find root (zero) of expression expr

print ("The price of", Stock_Ticker, "tripled after", sol, "years")

测试运行

Enter the stock ticker: xxxx
Enter Expected Annual Return: .1
Enter initial stock price: 1
The price of xxxx tripled after [11.5267046072476] years

学生卡在一个特定的方程求解问题上

Student stuck on a particular equation solver question

python

equation-solving