I'm just learning C++ and so I have started to make a simple program to approximate the value of pi, using the series: Pi ^ 6 / 960 = 1 + 1 / 3 ^ 6 + 1 / 5 ^ 6... and so on continuing with denominators of odd numbers to the power of 6. Here is my code:
/*-------------------------------------------
* AUTHOR: *
* PROGRAM NAME: Pi Calculator *
* PROGRAM FUNCTION: Uses an iterative *
* process to calculate pi to 16 *
* decimal places *
*------------------------------------------*/
#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
double pi_approximation = 0; // the approximated value of pi
double iteration = 3; // number used that increases to increase accuracy
double sum = 1; // the cumulative temporary total
int main ()
{
while (true) // endlessly loops
{
sum = sum + pow(iteration,-6); // does the next step in the series
iteration = iteration + 2; // increments iteration
pi_approximation = pow((sum * 960),(1 / 6)); // solves the equation for pi
cout << setprecision (20) << pi_approximation << "\n"; // prints pi to maximum precision permitted with a double
}
}
The code seems to work fine (both the variables 'sum' and 'iteration' increase correctly) up to this line here:
pi_approximation = pow((sum * 960),(1 / 6)); // solves the equation for pi
as for some reason 'pi_approximation' retains its value of 1 and as such the text printed to 'cout' is "1".
