#include <stdio.h>

#include <math.h>

double pi (void);

int main (void) {

printf ("Valor de PI: %f\n", pi () );

}

double pi (void) {

double valor_pi = 0, funcao;

int n;

for (n = 0; n < 10000000; n++){

funcao = 4 * pow(-1, n) / (2 * n + 1);

valor_pi = funcao + valor_pi;

}

return valor_pi;

}