meeting2017.md

@@ -41,8 +41,10 @@ IWR Heidelberg
   As a first step we will launch the RT implementation and try to add these
   one by one.
   * Add an interface to obtain a point-wise local transformation for the range space for each node. (e.g. the Piola-transformation for RT)
-  * Add an interface to obtain a linear basis transformation for each node. This allows, e.g., to flip basis functions (normal flip for RT), to permute basis functions or, in general, to transform to another local basis.
+  * Add an interface to obtain a linear basis transformation for each node. This allows, e.g., to flip basis functions (normal flip for RT), to permute basis functions or, in general, to transform to another local basis (Hermite elements). This should be exported as a matrix wrt the local basis function numbering in the node. Using special matrix types allows to express simple cases efficiently.
   * Add an interface to obtain a "global" finite element which already contains the range space transformation and the element geometry transformation of the domain. It should not contain the basis transformation, because this can be done more efficiently outside.
+  * Possible problems: Implementing the interpolation into the global space using only the local basis transformations may not lead to the expected natural interpolation for
+the corresponding FE-space, e.g., in case of Hermite-elements
 
 ### TypeTree
 * Add a method `treePath(...)` that does the same as `hybridTreePath()`