programming_tutorials/02_math_osztaly/math.cpp

#include "math.h"

float Math::inv_sqrt(const float x) {
	return (float)(1.0 / ::sqrtf(x));
}

float Math::fast_inv_sqrt(const float number) {
	long i;
	float x2, y;
	const float threehalfs = 1.5F;

	x2 = number * 0.5F;
	y = number;
	i = *(long *)&y;
	i = 0x5f3759df - (i >> 1);
	y = *(float *)&i;
	y = y * (threehalfs - (x2 * y * y));

	return y;
}

float Math::is_equal_approx(const float a, const float b) {
    if (a + EPSILON < b && a - EPSILON > b) {
		return true;
	}

	return false;
}

float Math::is_zero_approx(const float a) {
    if (a + EPSILON < 0 && a - EPSILON > 0) {
		return true;
	}

	return false;
}

void Math::seed(const unsigned int s) {
	srand(s);
}

void Math::randomize() {
	srand(time(NULL));
}

int Math::rand() {
	return rand();
}

float Math::randf() {
	return rand() / RANDOM_32BIT_MAX;
}

double Math::randd() {
	return rand() / RANDOM_32BIT_MAX;
}

int rand(const int m) {
    return rand() % m;
}

int rand(const int from, const int to) {
    return (rand() % (to - from)) + from;
}

float Math::rand(const float from, const float to) {
	return randf() * (to - from) + from;
}

float Math::rand(const double from, const double to) {
	return randd() * (to - from) + from;
}

/*


| + is_equal_approx(float a, float b) : bool { }      |  -> mint vektorban
| + is_zero_approx(float a) : bool { }                | 
|                                                            |
| + seed(unsigned int s) { }                          |  -> srand(s);
| + randomize() { }                                   |  -> srand(time(NULL));
|                                                            |
| + rand() : int { }                                  |  -> return rand();
| + randf() : float { }                               |  -> return rand() / RANDOM_32BIT_MAX;
| + randd() : float { }                               |  -> return rand() / RANDOM_32BIT_MAX;
|                                                            |
| + rand(float from, float to) : float { }            |  -> return randf() * to + from;
| + rand(double from, double to) : double { }         |  -> return randd() * to + from;
|------------------------------------------------------------|
*/