From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Thu, 20 Apr 2023 20:05:16 +0000 (-0600)
Subject: Add an example to the documentation of GridTools::transform().
X-Git-Tag: v9.5.0-rc1~304^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=efbc9e7291bedddc553ec437d08cd9e3bad3bf38;p=dealii.git

Add an example to the documentation of GridTools::transform().
---

diff --git a/include/deal.II/grid/grid_tools.h b/include/deal.II/grid/grid_tools.h
index c7b259c226..7bf25de6f9 100644
--- a/include/deal.II/grid/grid_tools.h
+++ b/include/deal.II/grid/grid_tools.h
@@ -555,7 +555,22 @@ namespace GridTools
    * predicate is either an object of a type that has an <tt>operator()</tt>,
    * or it is a pointer to a non-member function, or it is a lambda function
    * object. In either case, argument and return
-   * value have to be of type Point<spacedim>.
+   * value have to be of type Point<spacedim>. An example -- a simple
+   * transformation that moves the object two units to the
+   * right in the $x_1$ direction -- could look like as follows:
+   * @code
+   *   Triangulation<dim> triangulation;
+   *   ... // fill triangulation with something
+   *   GridTools::transform ([](const Point<dim> &p) -> Point<dim>
+   *                         {
+   *                           Point<dim> q = p;
+   *                           q[0] += 2;
+   *                           return q;
+   *                         },
+   *                         triangulation);
+   * @endcode
+   * Here, the transformation is provided by a lambda function that
+   * takes a `Point<dim>` as input and returns a `Point<dim>` as output.
    *
    * @note The transformations that make sense to use with this function
    *   should have a Jacobian with a positive determinant. For example,