Added Identity Function for Math lib

identity.hhs

@@ -0,0 +1,41 @@
+/**
+ * @author Mudroad White
+ * @param input - a positive integer denoting the size of the expected matrix.
+ * @returns - a Mat object representing a 2D identity matrix.
+ */
+
+function identity(input) {
+
+	*import math: is_number
+
+	// Corner cases for input
+	// First, input should be a positive integer
+	if (!Number.isInteger(input) || input < 0) {
+		throw new Error('Expecped positive integer input')
+	}
+
+	// Then we return special Mat value when input is 0 or 1
+	if (input === 0) {
+		return new Mat([]);
+	}
+
+	if (input === 1) {
+		return new Mat([[1]]);
+	}
+
+	// Now we can start on creating the Id matrix
+	let result = new Mat().zeros(n, n);
+	for (let i = 0; i < n; i++){
+		result[i][i] = 1;
+	}	
+
+	// return as a Mat object
+	return result;
+
+	// Note: the implementation of `result` above is for practicing purpose, from which I've learnt a lot.
+	// A better implementation suggested by the team is as follows, so feel free to alternate between the above 
+	// version and the following one.
+	// result = mathjs.identity(input);
+	// // return the result as a mat object
+	// return mat(result);
+}

identity_test.hhs

@@ -0,0 +1,26 @@
+/**
+ * @author Mudroad White
+ * @param 
+ * @returns 
+ *
+ * Functions for testing the identity function.
+ */
+
+function identity_test(){
+	*import math: identity
+
+	// Corner cases
+	if (!(identity(0) === new Mat([]))){
+		throw 'identity unit test failed on identity(0)';
+	}
+
+	if (!(identity(1) === new Mat([[1]]) )){
+		throw 'identity unit test failed on identity(1)';
+	}
+
+	// Ordinary case
+	const test1 = new Mat([[1, 0], [0, 1]]);
+	if (!(identity(2)) === test1){
+		throw 'identity unit test failed on identity(2)';
+	}
+}