pi

#include <stdio.h>
#include <stdlib.h>
#include <math.h>


long double approx1(int n);
long double approx2(int n);
long double approx3(int n);

int main()
{
    int num1;
    num1 = 0;

    printf("Enter number of terms to approximate pi to, or enter 0 to terminate: ");
    scanf("%d", &num1);
    puts(" ");

    while (num1 != 0)
    {
        if(num1 == 1)
        {    printf("First approximation of pi to %d term is %.8Lf \n\n", num1, approx1(num1));
             printf("Second approximation of pi to %d term is %.8Lf \n\n", num1, approx2(num1));
             printf("Third approximation of pi to %d term is %.8Lf \n\n", num1, approx3(num1));
        }
        else if (num1 > 1)
        {    printf("First approximation of pi to %d terms is %.8Lf \n\n", num1, approx1(num1));
             printf("Second approximation of pi to %d terms is %.8Lf \n\n", num1, approx2(num1));
             printf("Third approximation of pi to %d terms is %.8Lf \n\n", num1, approx3(num1));
        }
        else
            printf("Wrong input, please try again. \n");


        printf("Enter number of terms to approximate pi to, or enter 0 to terminate: ");
        scanf("%d", &num1);
    }

    printf("**Program Terminated***");

    return 0;
}


long double approx1(int n)
{
    long double pi, num, denom;
    pi = 0;
    denom = 1;
    num = 4;
    int i;


         for ( i = 1; i <= n; i = i + 1 )
         {
             if ( i % 2 != 0 ){
               pi = pi +  num / denom;
             }
             else {
               pi = pi - num / denom;
             }

             denom = denom + 2.0;
          }

    return pi;
}


long double approx2(int n)
{
    long double pi, num, denom;
    pi = 0;
    denom = 1;
    num = 1;
    int i;


         for ( i = 1; i <= n; i = i + 1 )
        {
            if (i % 2 != 0)
            {
                pi = pi + (12 * (num / (powl(denom, 2.0))));
            }
            else {
                pi = pi - (12 * (num / (powl(denom, 2.0))));
            }

            denom = denom + 1.0;
        }

    pi = sqrtl(pi);

    return pi;
}


long double approx3(int n)
{
    long double pi, num, denom, c1;
    pi = 0;
    num = 1;
    denom = 1;
    c1 = sqrtl(12.0);
    int i;


            for ( i = 0; i <= n; i = i + 1 )
            {
                if (i % 2 !=0)
                {
                    pi = pi -  (num/(denom*(powl(3.0, i))));
                }
                else {
                    pi = pi +  (num/(denom*(powl(3.0, i))));
                }

                denom = denom + 2.0;
            }

    return pi*c1;
}