Added a new math algorithm for triangular numbers name triangular_number.rs

Author: WinterPancake

src/math/mod.rs

@@ -78,6 +78,7 @@ mod sylvester_sequence;
 mod tanh;
 mod trapezoidal_integration;
 mod trial_division;
+mod triangular_number;
 mod trig_functions;
 mod vector_cross_product;
 mod zellers_congruence_algorithm;
@@ -170,6 +171,7 @@ pub use self::sylvester_sequence::sylvester;
 pub use self::tanh::tanh;
 pub use self::trapezoidal_integration::trapezoidal_integral;
 pub use self::trial_division::trial_division;
+pub use self::triangular_number::triangular_number;
 pub use self::trig_functions::cosine;
 pub use self::trig_functions::cosine_no_radian_arg;
 pub use self::trig_functions::cotan;

src/math/triangular_number.rs

@@ -0,0 +1,38 @@
+// Triangular Numbers: Function to the Nth Triangular Number
+// Wikipedia Reference : https://en.wikipedia.org/wiki/Triangular_number
+
+pub fn triangular_number(n: u64) -> u64 {
+    let m: u64 = (n | 1) * ((n + 1) / 2);
+    return m;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    macro_rules! test_triangular_number {
+        ($($name:ident: $inputs:expr,)*) => {
+        $(
+            #[test]
+            fn $name() {
+                let (n, expected) =$inputs;
+                assert_eq!(triangular_number(n), expected);
+            }
+        )*
+        }
+    }
+
+    test_triangular_number! {
+        input_0: (1, 1),
+        input_1: (2, 3),
+        input_2: (3, 6),
+        input_3: (4, 10),
+        input_4: (5, 15),
+        input_5: (6, 21),
+        input_6: (7, 28),
+        input_7: (8, 36),
+        input_8: (9, 45),
+        input_9: (10, 55),
+        input_10: (11, 66),
+    }
+}