c-exercises/approximate-pi.c

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#include <assert.h>
#include <stdio.h>
#include <stdbool.h>
double approximate_pi(unsigned int steps) {
double approximate_pi = 4.0;
bool subtract = true;
/* GregoryLeibniz series */
for (unsigned int i = 2; i <= steps; i++) {
if (subtract) {
approximate_pi -= (4.0 / (i * 2 - 1));
} else {
approximate_pi += (4.0 / (i * 2 - 1));
}
subtract = !subtract;
}
return approximate_pi;
}
int main(void) {
// printf("sizeof(int) = %d\n", sizeof(int));
double mypi = approximate_pi(100000000);
printf("pi = %8.7f\n", mypi);
assert(mypi > 3.141);
assert(mypi < 3.142);
return 0;
}