Question

如何在nthroot函数中询问用户输入？我希望函数可以询问输入x的幂和下一个项。（我希望程序要求权力和下一个学期，我只分别用3和81作为支票）

def derivative(f, x, h):
   return (f(x+h) - f(x-h)) / (2.0*h)  

def nthroot(x):
   return x**3 - 81   # just a function to show it works


def newraph(f, x0, h):
   Xold = x0
   Xnew = Xold + 10* h  
   while (abs(Xold - Xnew) > h):  
      Xold = Xnew 
      Xnew = Xold - f(Xnew) / derivative(f, Xold, h)  #NewtonRaphson formula
   return Xnew

trueroot = newraph(nthroot, 1, 0.000001)    
print "The root is", trueroot

当我尝试使用int（raw_input（））时：

def derivative(f, x, h):
  return (f(x+h) - f(x-h)) / (2.0*h)  

def nthroot(x):
   root = int(raw_input("Please Enter a nth root (n) : "))
   number =  int(raw_input("Please Enter a number (x): "))
   return x**(root) - (number)

def newraph(f, x0, h):
   Xold = x0
   Xnew = Xold + 10* h  
   while (abs(Xold - Xnew) > h):  
      Xold = Xnew 
      Xnew = Xold - f(Xnew) / derivative(f, Xold, h)  #NewtonRaphson formula
   return Xnew

trueroot = newraph(nthroot, 1, 0.000001)    
print "The root is", trueroot

输入的提示会重复多次。你是怎么结束的？

Answer 1

尝试动态生成Nthroot函数，其中包含所需的值。然后，这些值将在每个vall中重复使用到newraph中的“f”。

此方法允许您继续使用newraph的任意函数（即使您不需要用户输入或完全不同的输入）。

def derivative(f, x, h):
  return (f(x+h) - f(x-h)) / (2.0*h)  

def generateNthrootFunc():
   root = int(raw_input("Please Enter a nth root (n) : "))
   number =  int(raw_input("Please Enter a number (x): "))
   def nthroot(x):
      return x**(root) - (number)
   return nthroot

def newraph(f, x0, h):
   Xold = x0
   Xnew = Xold + 10* h  
   while (abs(Xold - Xnew) > h):  
      Xold = Xnew 
      Xnew = Xold - f(Xnew) / derivative(f, Xold, h)  #NewtonRaphson formula
   return Xnew

root = newraph(generateNthrootFunc(), 1, 0.000001)    # call the solver
print "The root is", root

Answer 2

输入的提示会重复多次......

因为你多次调用这个函数：

root = newraph(nthroot, 1, 0.000001)    # call the solver

然后在newraph

内

while (abs(Xold - Xnew) > h):  
  Xold = Xnew 
  Xnew = Xold - f(Xnew) / derivative(f, Xold, h)  #NewtonRaphson formula

其中f为nthroot。

然后你在derivate（两次）中称之为agin：

def derivative(f, x, h):
  return (f(x+h) - f(x-h)) / (2.0*h)

可行的解决方案

你可以让nthroot成为一个班级

class nthroot_generator:
    def __init__(self, number, root):
        self.number = number
        self.root = root
    def __call__(self, x):
        return x**(self.root) - (number)

并像这样呼吁：

root = int(input("Please Enter a nth root (n) : "))
number =  int(input("Please Enter a number (x): "))
trueroot = newraph(nthroot_generator(root, number), 1, 0.000001)

输入功能

2 个答案:

可行的解决方案