python-zx笔记3-函数

 1 # -*- coding: utf-8 -*-
 2 
 3 import math
 4 
 5 def quadratic(a, b, c):
 6     n = b*b - 4*a*c
 7     if n < 0:
 8         return ("此方程无解")
 9     elif n == 0:
10         return b/2*a
11     else:
12         x1 = (-b + math.sqrt(n))/(2*a)
13         x2 = (-b - math.sqrt(n))/(2*a)
14         return x1,x2
15 
16 # 测试:
17 print(quadratic(1,2,1))
18 print(quadratic(4,2,2))
19 
20 
21 # print(‘quadratic(2, 3, 1) =‘, quadratic(2, 3, 1))
22 # print(‘quadratic(1, 3, -4) =‘, quadratic(1, 3, -4))
23 # if quadratic(2, 3, 1) != (-0.5, -1.0):
24 #     print(‘测试失败‘)
25 # elif quadratic(1, 3, -4) != (1.0, -4.0):
26 #     print(‘测试失败‘)
27 # else:
28 #     print(‘测试成功‘)