Change implementation of to_row_vector for nalgebra (#34)

* Add failing test

* Change implementation of to_row_vector for nalgebra

src/linalg/naive/dense_matrix.rs

@@ -1064,6 +1064,12 @@ mod tests {
         );
     }
 
+    #[test]
+    fn col_matrix_to_row_vector() {
+        let m: DenseMatrix<f64> = BaseMatrix::zeros(10, 1);
+        assert_eq!(m.to_row_vector().len(), 10)
+    }
+
     #[test]
     fn iter() {
         let vec = vec![1., 2., 3., 4., 5., 6.];

src/linalg/nalgebra_bindings.rs

@@ -185,14 +185,15 @@ impl<T: RealNumber + 'static> BaseVector<T> for MatrixMN<T, U1, Dynamic> {
 impl<T: RealNumber + Scalar + AddAssign + SubAssign + MulAssign + DivAssign + Sum + 'static>
     BaseMatrix<T> for Matrix<T, Dynamic, Dynamic, VecStorage<T, Dynamic, Dynamic>>
 {
-    type RowVector = MatrixMN<T, U1, Dynamic>;
+    type RowVector = RowDVector<T>;
 
     fn from_row_vector(vec: Self::RowVector) -> Self {
         Matrix::from_rows(&[vec])
     }
 
     fn to_row_vector(self) -> Self::RowVector {
-        self.row(0).into_owned()
+        let (nrows, ncols) = self.shape();
+        self.reshape_generic(U1, Dynamic::new(nrows * ncols))
     }
 
     fn get(&self, row: usize, col: usize) -> T {
@@ -697,6 +698,12 @@ mod tests {
         assert_eq!(m.to_row_vector(), expected);
     }
 
+    #[test]
+    fn col_matrix_to_row_vector() {
+        let m: DMatrix<f64> = BaseMatrix::zeros(10, 1);
+        assert_eq!(m.to_row_vector().len(), 10)
+    }
+
     #[test]
     fn get_row_col_as_vec() {
         let m = DMatrix::from_row_slice(3, 3, &[1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]);

src/linalg/ndarray_bindings.rs

@@ -563,6 +563,12 @@ mod tests {
         );
     }
 
+    #[test]
+    fn col_matrix_to_row_vector() {
+        let m: Array2<f64> = BaseMatrix::zeros(10, 1);
+        assert_eq!(m.to_row_vector().len(), 10)
+    }
+
     #[test]
     fn add_mut() {
         let mut a1 = arr2(&[[1., 2., 3.], [4., 5., 6.]]);