Added error handling for elementwise functions

lib/matrix.js

@@ -13,6 +13,11 @@ class Matrix {
   }
 
   static subtract(a, b) {
+    if(a.rows!==b.rows || a.cols!==b.cols){
+      console.log('Columns and Rows of A must match Columns and Rows of B.');
+      return;
+    }
+
     // Return a new Matrix a-b
     return new Matrix(a.rows, a.cols)
       .map((_, i, j) => a.data[i][j] - b.data[i][j]);
@@ -34,7 +39,11 @@ class Matrix {
 
   add(n) {
     if (n instanceof Matrix) {
-      return this.map((e, i, j) => e + n.data[i][j]);
+      if(this.rows!==n.rows || this.cols!==n.cols){
+        console.log('Columns and Rows of A must match Columns and Rows of B.');
+        return;
+      }
+        return this.map((e, i, j) => e + n.data[i][j]);
     } else {
       return this.map(e => e + n);
     }
@@ -65,6 +74,11 @@ class Matrix {
 
   multiply(n) {
     if (n instanceof Matrix) {
+      if(this.rows!==n.rows || this.cols!==n.cols){
+        console.log('Columns and Rows of A must match Columns and Rows of B.');
+        return;
+      }
+
       // hadamard product
       return this.map((e, i, j) => e * n.data[i][j]);
     } else {

lib/matrix.test.js

@@ -223,6 +223,42 @@ test('mapping with instance map', () => {
   });
 });
 
+test('error handling of addition when columns and rows of A don\'t match columns and rows of B.', () => {
+  //Replace console.log with a jest mock so we can see if it has been called
+  global.console.log = jest.fn();
+
+  let m1 = new Matrix(1, 2);
+  let m2 = new Matrix(3, 4);
+  m1.add(m2);
+
+  //Check if the mock console.log has been called 
+  expect(global.console.log).toHaveBeenCalledWith('Columns and Rows of A must match Columns and Rows of B.')
+});
+
+test('error handling of static subtraction when columns and rows of A don\'t match columns and rows of B.', () => {
+  //Replace console.log with a jest mock so we can see if it has been called
+  global.console.log = jest.fn();
+
+  let m1 = new Matrix(1, 2);
+  let m2 = new Matrix(3, 4);
+  Matrix.subtract(m1,m2);
+
+  //Check if the mock console.log has been called
+  expect(global.console.log).toHaveBeenCalledWith('Columns and Rows of A must match Columns and Rows of B.')
+});
+
+test('error handling of hadamard product when columns and rows of A don\'t match columns and rows of B.', () => {
+  //Replace console.log with a jest mock so we can see if it has been called
+  global.console.log = jest.fn();
+
+  let m1 = new Matrix(1, 2);
+  let m2 = new Matrix(3, 4);
+  m1.multiply(m2);
+
+  //Check if the mock console.log has been called
+  expect(global.console.log).toHaveBeenCalledWith('Columns and Rows of A must match Columns and Rows of B.')
+});
+
 test('error handling of matrix product when columns of A don\'t match rows of B.', () => {
   //Replace console.log with a jest mock so we can see if it has been called
   global.console.log = jest.fn();
@@ -231,7 +267,7 @@ test('error handling of matrix product when columns of A don\'t match rows of B.
   let m2 = new Matrix(3, 4);
   Matrix.multiply(m1, m2);
 
-  //Check if the mock console.log has been called 
+  //Check if the mock console.log has been called
   expect(global.console.log).toHaveBeenCalledWith('Columns of A must match rows of B.')
 });