Question

我试图通过做各种小项目来学习python，在这种情况下，输入一个数字，pi将计算到该数字输入。在谷歌搜索的一些帮助下，我设法能够计算Pi，但无论我输入什么数字，它仍然会产生相同数量的Pi数字。

我有点困惑在什么地方导致这样做，任何提示都会非常感谢，提前感谢。这是在python 2.7

from math import factorial
from decimal import Decimal, getcontext
# Chudnovsky algorithm for figuring out pi
getcontext().prec=100

pi_input = input('How many digits of pi would you like?')
n = int(pi_input)

def calc(n):
    t= Decimal(0)
    pi = Decimal(0)
    deno= Decimal(0)

    for k in range(n):
        t = ((-1)**k)*(factorial(6*k))*(13591409+545140134*k)
        deno = factorial(3*k)*(factorial(k)**3)*(640320**(3*k))
        pi += Decimal(t)/Decimal(deno)
    pi = pi * Decimal(12) / Decimal(640320 ** Decimal(1.5))
    pi = 1/pi
    return pi

print calc(n)

这是我的输出

How many digits of pi would you like? 5

3.141592653589793238462643383279502884197169399375105820974944592307816346 94690247717268165239156011

Answer 1

使用Chudnovsky算法，计算每次迭代产生大约14.18个十进制数字：log10（（640320 ^ 3）/（24 * 6 * 2 * 6））〜= 14.18。这可以在本网页所示的_k / a _k-1的公式中更清楚地看到：

https://www.craig-wood.com/nick/articles/pi-chudnovsky

对于n = 5，结果大约有70位精度。

Answer 2

您可以使用"%.nf"格式化输出字符串，其中n是您要输出的位数。 e.g。

import numpy as np
print "%.5f"%(np.pi)

Answer 3

我只是在您的代码和希望的return语句中添加了舍入函数，它对您来说对我来说是有效的。

from math import factorial
from decimal import Decimal, getcontext
# Chudnovsky algorithm for figuring out pi
getcontext().prec=1000

pi_input = input('How many digits of pi would you like?')
n = int(pi_input)

def cal(n):
    t= Decimal(0)
    pi = Decimal(0)
    deno= Decimal(0)

    for k in range(n):
        t = ((-1)**k)*(factorial(6*k))*(13591409+545140134*k)
        deno = factorial(3*k)*(factorial(k)**3)*(640320**(3*k))
        pi += Decimal(t)/Decimal(deno)
    pi = pi * Decimal(12) / Decimal(640320 ** Decimal(1.5))
    pi = 1/pi
    return round(pi,n)

print(cal(n))

Answer 4

请尝试一下，让我知道它是否对您有用

import numpy as np

def pi_nth(n):
    new_str = ''
    for i in range(n+2):
        new_str += str(np.pi)[i]
    return float(new_str)

Answer 5

我使用数学模块中的PI简短地回答了同样的问题。

from math import pi
print()
nums = int(input("Enter the number of decimals: "))
print("Pi to the {}th number of decimals is %.{}f".format(nums, nums) % (pi))

输出

Enter the number of decimals: 5
Pi to the 5th number of decimals is 3.14159

这是python 3.8希望对您有所帮助。

Answer 6

from math import factorial
from decimal import Decimal, getcontext

n = int(input('How many digits of pi would you like?'))
# Chudnovsky algorithm for figuring out pi
getcontext().prec=n+1
def calc(n):
    t= Decimal(0)
    pi = Decimal(0)
    deno= Decimal(0)
    k=0

    #t = ((-1)**k)*(factorial(6*k))*(13591409+545140134*k)
    t=(1)*(factorial(1))*(13591409+545140134*k)
    deno = factorial(3*k)*(factorial(k)**3)*(640320**(3*k))
    pi += Decimal(t)/Decimal(deno)
    pi = pi * Decimal(12) / Decimal(640320 ** Decimal(1.5))
    pi = 1/pi
    return pi

print (calc(n))

Answer 7

这可能是理解的简单代码

from numpy import *

n = int(input('How many digits of pi after decimal would you like to print'))
print(pi)

#print (" value of pi at {:.4f} is" .format(pi))

print('{pi:0.{precision}f}'.format(pi=pi,precision=n))

Answer 8

这就是我要做的:-)

import math
digits = int(input("to how many digits to you want to round PI?"))

def roundpi(n):
    return round(pi,n)

roundpi(digits)

Answer 9

#To print the Nth decimal place values of pi
from math import pi
#Receive the input value for number of decimal points of pi needed from user
i=input("Enter the number of decimal places needed in pi")
#Variable to hold the pi value upto nth decimal.Assign it to empty string initially
n_val=""
#Convert the pi value to string 
string_pi=str(pi) 

    x=0
    #loop through each literals and add the value to a string variable and then print it
    while x<=int(i)+1:
        n_val+=string_pi[x]
        x=x+1
    print(n_val)

Answer 10

from math import pi

num = int(input('Enter the number of decimals: '))

print(f"Pi upto {num}th number is {pi:{1}.{num+1}}")

计算Pi到第N位

10 个答案: