Minor documentation fixes.

Fix #174.

src/structs/dmat.rs

@@ -108,7 +108,7 @@ impl<N: Clone + Copy> DMat<N> {
 }
 
 impl<N> DMat<N> {
-    /// Builds a matrix using an initialization function.
+    /// Builds a matrix filled with the results of a function applied to each of its component coordinates.
     #[inline(always)]
     pub fn from_fn<F: FnMut(usize, usize) -> N>(nrows: usize, ncols: usize, mut f: F) -> DMat<N> {
         DMat {

src/structs/dvec.rs

@@ -54,7 +54,7 @@ impl<N: Clone> DVec<N> {
 }
 
 impl<N> DVec<N> {
-    /// Builds a vector filled with the result of a function.
+    /// Builds a vector filled with the results of a function applied to each of its component coordinates.
     #[inline(always)]
     pub fn from_fn<F: FnMut(usize) -> N>(dim: usize, mut f: F) -> DVec<N> {
         DVec { at: (0..dim).map(|i| f(i)).collect() }