to1DArray() {
                var array = new Array(this.size);
                for (var i = 0; i < this.rows; i++) {
                    for (var j = 0; j < this.columns; j++) {
                        array[i * this.columns + j] = this.get(i, j);
                    }
                }
                return array;
            }
Returns a new 1D array filled row by row with the matrix values
@return {Array}