Adding generate functionality

Author: raghav-coding

README.md

@@ -132,3 +132,14 @@ B = matrix([[3,4], [1,2]]);
 A.equals(B);
 // returns false
 ```
+
+#### 19. Generate
+Generates a matrix with the value passed across the entire matrix or just the diagonal.
+```javascript
+matrix.gen(4).size(2,3); // returns [[4,4,4],[4,4,4]]
+matrix.gen(2).size(2); // returns [[2,2],[2,2]]
+matrix.gen(1).diag(3); // return [[1,0,0],[0,1,0],[0,0,1]], identity matrix
+// Diagonal matrices are normally square. Here, only diagonal elements are filled where row and column indices are same. 
+matrix.gen(1).diag(3,2); // returns [[1,0],[0,1],[0,0]]
+matrix.gen(2).diag(3,4); // returns [[2,0,0,0],[0,2,0,0],[0,0,2,0]
+```

lib/generate.js

@@ -0,0 +1,43 @@
+'use strict';
+
+function generate(val) {
+    return {
+        size: (row, col) => size(val, row, col),
+        diag: (row, col) => diag(val, row, col)
+    }
+}
+
+function size(val, row, col) {
+    if (!col) {
+        col = row;
+    }
+    let rows = [];
+    for (let i = 0; i < row; i++) {
+        let cols = [];
+        for (let j = 0; j < col; j++) {
+            cols[j] = val; 
+        }
+        rows[i] = cols;
+    }
+    return rows;
+}
+
+function diag(val, row, col) {
+    if (!col) {
+        col = row;
+    }
+    let rows = [];
+    for (let i = 0; i < row; i++) {
+        let cols = [];
+        for (let j = 0; j < col; j++) {
+            cols[j] = 0; 
+        }
+        rows[i] = cols;
+        if (i < col || row == col) {
+            rows[i][i] = val;
+        }
+    }
+    return rows;
+}
+
+module.exports = generate;

lib/index.js

@@ -2,6 +2,7 @@
 
 const rational = require('./rational');
 const merge = require('./merge');
+const generate = require('./generate');
 
 /**
  * Pass a 2-dimensional array that will return a function accepting indices to access the matrix
@@ -20,6 +21,7 @@ function matrix(mat) {
     return Object.assign(_matrix, _mat(mat));
 }
 
+matrix.gen = generate;
 
 /**
  * Private function that returns an object containing methods
@@ -511,7 +513,7 @@ function derationalize(mat) {
  * @param val specified value
  * @returns square matrix
  */
-function generate(size, val) {
+function _generate(size, val) {
     let dim = 2;
     while (dim > 0) {
         var arr = [];
@@ -535,7 +537,7 @@ function generate(size, val) {
  * @returns identity matrix
  */
 function identity(size) {
-    let result = generate(size, 0);
+    let result = _generate(size, 0);
     result.forEach((row, index) => {
         row[index] = 1;
     });

package-lock.json

@@ -1,6 +1,6 @@
 {
     "name": "matrix-js",
-    "version": "1.6.1",
+    "version": "1.7.0",
     "description": "A Javascript Library to perform basic matrix operations using the functional nature of Javascript",
     "main": "lib",
     "directories": {

package.json

@@ -153,4 +153,12 @@ describe('Matrix operations', () => {
         assert.equal(A.equals(B), false);
         assert.equal(C.equals(C), true);
     });
+
+    it('should generate a matrix', () => {
+        assert.deepEqual(matrix.gen(4).size(2,3), [[4,4,4],[4,4,4]]);
+        assert.deepEqual(matrix.gen(2).size(2), [[2,2],[2,2]]);
+        assert.deepEqual(matrix.gen(1).diag(3,2), [[1,0],[0,1],[0,0]]);
+        assert.deepEqual(matrix.gen(2).diag(3,4), [[2,0,0,0],[0,2,0,0],[0,0,2,0]]);
+        assert.deepEqual(matrix.gen(1).diag(3), [[1,0,0],[0,1,0],[0,0,1]]);
+    });
 });