diff --git a/src/dmat.rs b/src/dmat.rs
index 41142f17..16e700fb 100644
--- a/src/dmat.rs
+++ b/src/dmat.rs
@@ -63,6 +63,16 @@ impl<N> DMat<N> {
             mij:   vec::from_fn(nrows * ncols, |i| { let m = i % ncols; f(m, m - i * ncols) })
         }
     }
+
+    /// The number of row on the matrix.
+    pub fn nrows(&self) -> uint {
+        self.nrows
+    }
+
+    /// The number of columns on the matrix.
+    pub fn ncols(&self) -> uint {
+        self.ncols
+    }
 }
 
 // FIXME: add a function to modify the dimension (to avoid useless allocations)?
diff --git a/src/dvec.rs b/src/dvec.rs
index 5caee856..7931543d 100644
--- a/src/dvec.rs
+++ b/src/dvec.rs
@@ -59,19 +59,29 @@ impl<N: Clone> DVec<N> {
     }
 }
 
+impl<N> Container for DVec<N> {
+    #[inline]
+    fn len(&self) -> uint {
+        self.at.len()
+    }
+}
+
 impl<N> Iterable<N> for DVec<N> {
+    #[inline]
     fn iter<'l>(&'l self) -> VecIterator<'l, N> {
         self.at.iter()
     }
 }
 
 impl<N> IterableMut<N> for DVec<N> {
+    #[inline]
     fn mut_iter<'l>(&'l mut self) -> VecMutIterator<'l, N> {
         self.at.mut_iter()
     }
 }
 
 impl<N> FromIterator<N> for DVec<N> {
+    #[inline]
     fn from_iterator<I: Iterator<N>>(mut param: &mut I) -> DVec<N> {
         let mut res = DVec { at: ~[] };