atan2_acos_test.c

#include <stdio.h>
#include <limits.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>

#define Random0to1 ((double) rand() / (RAND_MAX)) + 1
#define ITERATION 100000000

double get_time_milli() {
	struct timeval  tv;
	gettimeofday(&tv, NULL);
	return (tv.tv_sec) * 1000 + (tv.tv_usec) / 1000;
}

int main() {
	double prev, curr;

	prev = get_time_milli();
	for( int i = 0; i < ITERATION; i ++ ) {
		double x = Random0to1;
		double y = Random0to1;

		double rad = atan2(y, x);
	}
	curr = get_time_milli();
	printf("atan2 : diff = %lf\n", curr - prev);

	prev = get_time_milli();
	for( int i = 0; i < ITERATION; i ++ ) {
		double x = Random0to1;
		double y = Random0to1;

		// x축 증가하는 방향 단위 벡터와의 내적
		double rad = acos(x / (1 * sqrt(pow(x, 2) + pow(y, 2))));
	}
	curr = get_time_milli();
	printf("acos : diff = %lf\n", curr - prev);

	return 0;
}