From 27c4a8063178db79f3979b4f58a5d005977e74d7 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Thu, 13 Apr 2017 20:51:47 -0700
Subject: [PATCH] Add gcd() and lcm() methods to Int

---
 types/src/number/math.rs | 66 ++++++++++++++++++++++++++++++++++++++++
 types/src/number/mod.rs  |  1 +
 2 files changed, 67 insertions(+)
 create mode 100644 types/src/number/math.rs

diff --git a/types/src/number/math.rs b/types/src/number/math.rs
new file mode 100644
index 0000000..bf9aef2
--- /dev/null
+++ b/types/src/number/math.rs
@@ -0,0 +1,66 @@
+/* types/src/number/math.rs
+ * Eryn Wells <eryn@erynwells.me>
+ */
+
+use number::Int;
+
+pub trait GCD {
+    /// Find the greatest common divisor of `self` and another number.
+    fn gcd(self, other: Self) -> Self;
+}
+
+pub trait LCM {
+    /// Find the least common multiple of `self` and another number.
+    fn lcm(self, other: Self) -> Self;
+}
+
+impl GCD for Int {
+    fn gcd(self, other: Int) -> Int {
+		let (mut a, mut b) = if self > other {
+			(self, other)
+		} else {
+			(other, self)
+		};
+
+		while b != 0 {
+			let r = a % b;
+			a = b;
+			b = r;
+		}
+
+		a
+    }
+}
+
+impl LCM for Int {
+    fn lcm(self, other: Int) -> Int {
+        if self == 0 && other == 0 {
+            0
+        }
+        else {
+            self * other / self.gcd(other)
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{LCM, GCD};
+
+    #[test]
+    fn gcd_works() {
+        assert_eq!(0, 0.gcd(0));
+        assert_eq!(10, 10.gcd(0));
+        assert_eq!(10, 0.gcd(10));
+        assert_eq!(10, 10.gcd(20));
+        assert_eq!(44, 2024.gcd(748));
+    }
+
+    #[test]
+    fn lcm_works() {
+        assert_eq!(0, 0.lcm(0));
+        assert_eq!(0, 10.lcm(0));
+        assert_eq!(0, 10.lcm(0));
+        assert_eq!(42, 21.lcm(6));
+    }
+}
diff --git a/types/src/number/mod.rs b/types/src/number/mod.rs
index 0233c47..b768631 100644
--- a/types/src/number/mod.rs
+++ b/types/src/number/mod.rs
@@ -9,6 +9,7 @@
 pub mod real;
 pub mod complex;
 mod add;
+mod math;
 
 pub use self::real::Real;
 pub use self::complex::Complex;