python – 任何人都可以告诉我为什么我的代码显示错误的pi值？

发布时间：2020-12-20 13:09:47 所属栏目：Python 来源：网络整理

导读：这是我输出的图片： inptTol = float(input("Enter the tolerance: "))print()term = 1divNum = 3npower = 1sumPi = 0.0count = 0while abs(term) inptTol: sumPi += term term = -term/(divNum * (3**npower)) divNum += 2 npower += 1 count += 1sumPi = m

This is the equation i'm trying to use in the while loop

这是我输出的图片：

enter image description here

inptTol = float(input("Enter the tolerance: "))
print()

term = 1
divNum = 3
npower = 1
sumPi = 0.0
count = 0

while abs(term) > inptTol:
    sumPi += term
    term = -term/(divNum * (3**npower))
    divNum += 2
    npower += 1
    count += 1

sumPi = math.sqrt(12) * sumPi  
pythonPi = math.pi  
approxError = abs (sumPi - pythonPi)  

print("The approximate value of pi is %.14en" 
        "       Python's value of pi is %.14en"
        "The error in the approximation of pi is %.6en"
        "The number of terms used to calculate the value of pi is %g " %
        (sumPi,pythonPi,approxError,count))

这些是它显示的值：

pi的近似值是3.08770957930231e 00

Python的pi值是3.14159265358979e 00

我希望它能告诉我这个：

pi的近似值是3.14159265358979

Python的pi值是3.14159265358979

解决方法

至于我的问题是因为你改变了术语价值.它必须是1或-1 – 符号.

我的版本 – 我用于循环

import math

terms_number = float(input("Enter terms number: "))

sign = 1
divNum = 1
npower = 0
sumPi = 0.0
count = 0

for x in range(terms_number):

    sumPi += sign/(divNum * (3**npower))

    # values for next term
    sign = -sign
    divNum += 2
    npower += 1
    count += 1


sumPi = math.sqrt(12) * sumPi  
pythonPi = math.pi  
approxError = abs (sumPi - pythonPi)  

print("The approximate value of pi is %.14en" 
        "       Python's value of pi is %.14en"
        "The error in the approximation of pi is %.6en"
        "The number of terms used to calculate the value of pi is %g " %
        (sumPi,count))

结果为7个学期

The approximate value of pi is 3.14167431269884e+00
       Python's value of pi is 3.14159265358979e+00
The error in the approximation of pi is 8.165911e-05
The number of terms used to calculate the value of pi is 7

结果为15个学期

The approximate value of pi is 3.14159265952171e+00
       Python's value of pi is 3.14159265358979e+00
The error in the approximation of pi is 5.931921e-09
The number of terms used to calculate the value of pi is 15

编辑：带有while循环的版本

import math

inptTol = float(input("Enter the tolerance: "))
term = 1

sign = 1
divNum = 1
npower = 0
sumPi = 0.0
count = 0

while abs(term) > inptTol:

    term = sign/(divNum * (3**npower))

    sumPi += term

    # values for next term
    sign = -sign
    divNum += 2
    npower += 1
    count += 1


sumPi = math.sqrt(12) * sumPi  
pythonPi = math.pi  
approxError = abs (sumPi - pythonPi)  

print("The approximate value of pi is %.14en" 
        "       Python's value of pi is %.14en"
        "The error in the approximation of pi is %.6en"
        "The number of terms used to calculate the value of pi is %g " %
        (sumPi,count))

（编辑：李大同）

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