Dense Matrix resize

lib/type/Matrix.js

@@ -82,12 +82,16 @@ module.exports = function (config) {
   };
 
   /**
-   * Resize the matrix
-   * @param {Number[]} size
+   * Resize the matrix to the given size. Returns a copy of the matrix when 
+   * `copy=true`, otherwise return the matrix itself (resize in place).
+   *
+   * @param {Number[]} size           The new size the matrix should have.
    * @param {*} [defaultValue=0]      Default value, filled in on new entries.
    *                                  If not provided, the matrix elements will
    *                                  be filled with zeros.
-   * @return {Matrix} self            The matrix itself is returned
+   * @param {boolean} [copy]          Return a resized copy of the matrix
+   *
+   * @return {Matrix}                 The resized matrix
    */
   Matrix.prototype.resize = function (size, defaultValue) {
     // must be implemented by each of the Matrix implementations

lib/type/matrix/CcsMatrix.js

@@ -395,7 +395,7 @@ module.exports = function (math) {
   };
   
   /**
-   * Resize the matrix to the given size. Returns a copy of the matrix when the 
+   * Resize the matrix to the given size. Returns a copy of the matrix when 
    * `copy=true`, otherwise return the matrix itself (resize in place).
    *
    * @param {Number[]} size           The new size the matrix should have.
@@ -404,7 +404,7 @@ module.exports = function (math) {
    *                                  be filled with zeros.
    * @param {boolean} [copy]          Return a resized copy of the matrix
    *
-   * @return {CcsMatrix}              The resized matrix
+   * @return {Matrix}                 The resized matrix
    */
   CcsMatrix.prototype.resize = function (size, defaultValue, copy) {
     // validate arguments

lib/type/matrix/DenseMatrix.js

@@ -326,19 +326,30 @@ module.exports = function (math) {
   }
   
   /**
-   * Resize the matrix
-   * @param {Number[]} size
+   * Resize the matrix to the given size. Returns a copy of the matrix when
+   * `copy=true`, otherwise return the matrix itself (resize in place).
+   *
+   * @param {Number[]} size           The new size the matrix should have.
    * @param {*} [defaultValue=0]      Default value, filled in on new entries.
    *                                  If not provided, the matrix elements will
    *                                  be filled with zeros.
-   * @return {DenseMatrix} self            The matrix itself is returned
+   * @param {boolean} [copy]          Return a resized copy of the matrix
+   *
+   * @return {Matrix}                 The resized matrix
    */
-  DenseMatrix.prototype.resize = function (size, defaultValue) {
-    this._size = object.clone(size);
-    this._data = array.resize(this._data, this._size, defaultValue);
-
-    // return the matrix itself
-    return this;
+  DenseMatrix.prototype.resize = function (size, defaultValue, copy) {
+    // matrix to resize
+    var m = copy ? this.clone() : this;
+    // resize matrix
+    return _resize(m, size, defaultValue);
+  };
+  
+  var _resize = function (matrix, size, defaultValue) {
+    // resize matrix
+    matrix._size = object.clone(size);
+    matrix._data = array.resize(matrix._data, matrix._size, defaultValue);
+    // return matrix
+    return matrix;
   };
   
   /**
@@ -369,7 +380,7 @@ module.exports = function (math) {
 
     if (changed) {
       // resize only when size is changed
-      matrix.resize(newSize, defaultValue);
+      _resize(matrix, newSize, defaultValue);
     }
   }
   

test/type/matrix/DenseMatrix.test.js

@@ -171,6 +171,36 @@ describe('DenseMatrix', function() {
       m.resize([3], math.uninitialized);
       assert.deepEqual(m.valueOf(), arr(uninit, uninit, uninit));
     });
+    
+    it('should return a different matrix when copy=true', function() {
+      var m1 = new DenseMatrix(
+        [
+          [0, 0, 0, 0],
+          [0, 0, 0, 0],
+          [0, 0, 0, 0],
+          [0, 0, 0, 0]
+        ]);
+      var m2 = m1.resize([2, 2], 0, true);
+      assert(m1 !== m2);
+      // original matrix cannot be modified
+      assert.deepEqual(m1._size, [4, 4]);
+      assert.deepEqual(
+        m1._data, 
+        [
+          [0, 0, 0, 0],
+          [0, 0, 0, 0],
+          [0, 0, 0, 0],
+          [0, 0, 0, 0]
+        ]);
+      // new matrix should have correct size
+      assert.deepEqual(m2._size, [2, 2]);
+      assert.deepEqual(
+        m2._data, 
+        [
+          [0, 0],
+          [0, 0]
+        ]);
+    });
   });
   
   describe('get', function () {