lab1_q5

#include <stdio.h>
#include <stdlib.h>
/* Calculate the value of from the infinite series PI = 4-(4/3)+(4/5)-(4/7)+......
Write  a  program  which  reads  in  a  positive  integer  n(i.e.,  n>=1)and  calculates  the  value  of by adding up the first n terms of the above series */
int main()
{  /* This program will calculate and print the value of
    pi up to the first n terms using an infinite series */
    int n,i=0;
    float x=0,sum1=0,sign=-1;
    printf("Please input a positive integer, greater than or equal to 1 ");
    scanf("%d",&n);
    do{ //A do while loop is used here to to calculate the sum of pi.
        i++;
        sign = sign*-1;
        sum1 = sum1 +(4/(2*x+1))*sign; // an infinite series is used here, to calculate the sum of pi
        x ++;
    }while(i<n); // runs while i is less that n (inputted intger)
printf("%f",sum1);
return 0;
}