From: Wolfgang Bangerth Date: Wed, 19 Apr 2017 19:31:06 +0000 (-0600) Subject: Minor doc update to TriaAccessor::center. X-Git-Tag: v9.0.0-rc1~1662^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F4289%2Fhead;p=dealii.git Minor doc update to TriaAccessor::center. --- diff --git a/include/deal.II/grid/tria_accessor.h b/include/deal.II/grid/tria_accessor.h index 37798404f6..1445bd296f 100644 --- a/include/deal.II/grid/tria_accessor.h +++ b/include/deal.II/grid/tria_accessor.h @@ -1270,19 +1270,25 @@ public: /** * Center of the object. The center of an object is defined to be the - * average of the locations of the vertices. If required, the user may ask - * this function to return the average of the point according to the - * underlying Manifold object, by setting to true the optional parameter @p - * respect_manifold. + * average of the locations of the vertices, which is also where a $Q_1$ + * mapping would map the center of the reference cell. However, you can also + * ask this function to instead return the average of the vertices as + * computed by the underlying Manifold object associated with the current + * object, by setting to true the optional parameter @p respect_manifold. + * Manifolds would then typically pull back the coordinates of the vertices + * to a reference domain (not necessarily the reference cell), compute the + * average there, and then push forward the coordinates of the averaged + * point to the physical space again; the resulting point is guaranteed to + * lie within the manifold, even if the manifold is curved. * * When the geometry of a TriaAccessor is not flat, or when part of the * bounding objects of this TriaAccessor are not flat, the result given by * the TriaAccessor::center() function may not be accurate enough, even when * parameter @p respect_manifold is set to true. If you find this to be * case, than you can further refine the computation of the center by - * setting to true the second additional parameter @p - * use_laplace_transformation, which will force this function to compute the - * location of the center by solving a linear elasticity problem with + * setting to true the second additional parameter + * @p use_laplace_transformation, which will force this function to compute + * the location of the center by solving a linear elasticity problem with * Dirichlet boundary conditions set to the location of the bounding * vertices and the centers of the bounding lines and quads. */