Java Utililty Methods gcd

double epsilon = 1.0 / (1L << 32);
while (a > epsilon) {
    if (a < b) {
        double swap = a;
        a = b;
        b = swap;
    a = a % b;
...

return b == 0 ? a : GCD(b, a % b);

if (b == 0) {
    return a;
} else {
    return gcd(b, a % b);

Gets the greatest common divisor of the absolute value of two numbers, using the "binary gcd" method which avoids division and modulo operations.

int u = p;
int v = q;
if ((u == 0) || (v == 0)) {
    if ((u == Integer.MIN_VALUE) || (v == Integer.MIN_VALUE)) {
        return 0;
    return (Math.abs(u) + Math.abs(v));
if (u > 0) {
    u = -u;
if (v > 0) {
    v = -v;
int k = 0;
while ((u & 1) == 0 && (v & 1) == 0 && k < 31) { 
    u /= 2;
    v /= 2;
    k++; 
if (k == 31) {
    return 0;
int t = ((u & 1) == 1) ? v : -(u / 2);
do {
    while ((t & 1) == 0) { 
        t /= 2; 
    if (t > 0) {
        u = -t;
    } else {
        v = t;
    t = (v - u) / 2;
} while (t != 0);
return -u * (1 << k); 

while (b != 0) {
    int h = a % b;
    a = b;
    b = h;
return a;

return b == 0 ? a : gcd(b, a % b);

if (a > b) {
    int tmp = a;
    a = b;
    b = tmp;
if (a == 0) {
    return 0;
if (b % a == 0) {
    return a;
return gcd(b % a, a);

return (b == 0) ? a : gcd(b, a % b);

int min = Math.min(a, b);
int max = Math.max(a, b);
int r = max % min;
if (r == 0) {
    return min;
} else {
    return gcd(min, r);

a = Math.abs(a);
b = Math.abs(b);
while (a > 0) {
    int c = b % a;
    b = a;
    a = c;
return b;
...