Better document IdentityFunction.

This came up in review but wasn't fixed before it got merged.

diff --git a/include/deal.II/base/function.h b/include/deal.II/base/function.h
index e3ec0fc127a8ff29e89b1fe49ca18e0f4878bd19..d0eb74fa69a6c4ab8fd3b5a7400903d9f9b309af 100644 (file)
--- a/include/deal.II/base/function.h
+++ b/include/deal.II/base/function.h
@@ -520,8 +520,9 @@ namespace Functions
    * A function whose output is also its input. One possible application of this
    * function is interpolating or projecting a finite element field that
    * represents spatial coordinates: e.g., one can set up a finite element field
-   * to interpolate the vertices of a Triangulation with this function, which is
-   * useful when doing calculations in a Lagrangian reference frame.
+   * to interpolate the positions of a Triangulation's cells with this function
+   * (via VectorTools::interpolate()), which is useful when doing calculations
+   * in a Lagrangian reference frame.
    *
    * @ingroup functions
    */