本文实例讲述了python实现计算倒数的方法。分享给大家供大家参考。具体如下：
class expr:
def __add__(self, other):
return plus(self, other)
def __mul__(self, other):
return times(self, other)
class int(expr):
def __init__(self, n):
self.n = n
def d(self, v):
return int(0)
def __str__(self):
return `self.n`
class var(expr):
def __init__(self, var):
self.var = var
def d(self, v):
return int(self.var == v and 1 or 0)
def __str__(self):
return self.var
class plus(expr):
def __init__(self, a, b):
self.e1 = a
self.e2 = b
def d(self, v):
return plus(self.e1.d(v), self.e2.d(v))
def __str__(self):
return “(%s + %s)” % (self.e1, self.e2)
class times(expr):
def __init__(self, a, b):
self.e1 = a
self.e2 = b
def d(self, v):
return plus(times(self.e1, self.e2.d(v)), times(self.e1.d(v), self.e2))
def __str__(self):
return “(%s * %s)” % (self.e1, self.e2)
if __name__ == “__main__”:
x = var(“x”)
a = var(“a”)
b = var(“b”)
c = var(“c”)
e = a * x * x + b * x + c
print “d(%s, x) = %s” % (e, e.d(“x”))
希望本文所述对大家的python程序设计有所帮助。