Merge branch 'main' into mscroggs/doc-updates

Author: mscroggs

src/traits.rs

@@ -33,11 +33,15 @@ pub trait FiniteElement {
     fn dim(&self) -> usize;
 
     /// The shape of the values returned by functions in $\mathcal{V}$.
+    ///
+    /// If the values are scalar an empty slice is returned.
     fn value_shape(&self) -> &[usize];
 
     /// The number of values returned.
     ///
     /// If (for example) `value_shape` is `[3, 4]` then `value_size` is $3\times4 = 12$.
+    /// If `value_shape` returns an empty array (ie the shape functions are scalar) the
+    // convention is used that the product of the elements of an empty array is 1.
     fn value_size(&self) -> usize;
 
     /// Tabulate the values of the basis functions and their derivatives at a set of points