关于循环：在c ++中使用taylor系列计算Pi的函数

Function for calculating Pi using taylor series in c++

所以我对我的代码不起作用的原因一无所知，本质上，我编写的函数使用泰勒级数来计算π的估计值，只要我运行程序，它就会崩溃。

这是我的密码

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#include <iostream>
#include <math.h>
#include <stdlib.h>
using namespace std;

double get_pi(double accuracy)
{
double estimate_of_pi, latest_term, estimated_error;
int sign = -1;
int n;

estimate_of_pi = 0;
n = 0;

do
{
sign = -sign;
estimated_error = 4 * abs(1.0 / (2*n + 1.0)); //equation for error
latest_term = 4 * (1.0 *(2.0 * n + 1.0)); //calculation for latest term in series
estimate_of_pi = estimate_of_pi + latest_term; //adding latest term to estimate of pi
n = n + 1; //changing value of n for next run of the loop
}
while(abs(latest_term)< estimated_error);

return get_pi(accuracy);

}

int main()
{
cout << get_pi(100);
}

代码背后的逻辑如下：

定义所有变量

将pi的估计值设置为0

从泰勒级数中计算一个项，并计算这个术语

然后在pi的估计中加上最新的术语。

然后，程序应该计算出序列中的下一个项和其中的错误，并将其添加到pi的估计中，直到while语句中的条件得到满足为止。

谢谢你的帮助

您的函数中有几个错误。查看我的注释，行以"//note："开头。

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double get_pi(double accuracy)
{
double estimate_of_pi, latest_term, estimated_error;
int sign = -1;
int n;

estimate_of_pi = 0;
n = 0;

do
{
sign = -sign;

//NOTE: This is an unnecessary line.
estimated_error = 4 * abs(1.0 / (2*n + 1.0)); //equation for error

//NOTE: You have encoded the formula incorrectly.
// The RHS needs to be "sign*4 * (1.0 /(2.0 * n + 1.0))"
// ^^^^ ^
latest_term = 4 * (1.0 *(2.0 * n + 1.0)); //calculation for latest term in series
estimate_of_pi = estimate_of_pi + latest_term; //adding latest term to estimate of pi
n = n + 1; //changing value of n for next run of the loop
}

//NOTE: The comparison is wrong.
// The conditional needs to be"fabs(latest_term) > estimated_error"
// ^^^^ ^^^
while(abs(latest_term)< estimated_error);

//NOTE: You are calling the function again.
// This leads to infinite recursion.
// It needs to be "return estimate_of_pi;"
return get_pi(accuracy);
}

另外，main中的函数调用是错误的。它需要：

1	get_pi(0.001)

如果项的绝对值小于0.001，则函数可以返回。

这是一个适用于我的函数的更新版本。

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double get_pi(double accuracy)
{
double estimate_of_pi, latest_term;
int sign = -1;
int n;

estimate_of_pi = 0;
n = 0;

do
{
sign = -sign;
latest_term = sign * 4 * (1.0 /(2.0 * n + 1.0)); //calculation for latest term in series
estimate_of_pi += latest_term; //adding latest term to estimate of pi
++n; //changing value of n for next run of the loop
}
while(fabs(latest_term) > accuracy);

return estimate_of_pi;
}