Leibniz function in c

Question

I'm looking for a Leibniz approximation of PI in C.

I've tested this function but it does not seem to work:

float leibnizPi(float n){
    double pi=1.0;
    int i;
    int N;
    for (i=3, N=2*n+1; i<=N; i+=2)
        pi += ((i&2) ? -1.0 : 1.0) / i;
    return 4*pi;
}

Answer 1

I've tested you function and it seems to work fine. For n=1000, I get a result of 3.142592.

How I've tested the function:

#include <stdio.h>

float leibnizPi(float n) {
    double pi=1.0;
    int i;
    int N;
    for (i=3, N=2*n+1; i<=N; i+=2)
        pi += ((i&2) ? -1.0 : 1.0) / i;
    return 4*pi;
}

int main(void)
{
    printf("Pi: %f\n", leibnizPi(1000));
    return 0;
}