From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Mon, 21 Mar 2011 16:47:31 +0000 (+0000)
Subject: Add documentation.
X-Git-Tag: v8.0.0~4216
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b1e5baee30db983070a169f408546d209f36900b;p=dealii.git

Add documentation.


git-svn-id: https://svn.dealii.org/trunk@23486 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/include/deal.II/fe/fe_values.h b/deal.II/include/deal.II/fe/fe_values.h
index c5e0b52aad..1fcf713bef 100644
--- a/deal.II/include/deal.II/fe/fe_values.h
+++ b/deal.II/include/deal.II/fe/fe_values.h
@@ -148,9 +148,9 @@ namespace FEValuesExtractors
 
 				   /**
 				    * Extractor for a vector of
-				    * <code>dim</code> components of a
+				    * <code>spacedim</code> components of a
 				    * vector-valued element. The value of
-				    * <code>dim</code> is defined by the
+				    * <code>spacedim</code> is defined by the
 				    * FEValues object the extractor is applied
 				    * to.
 				    *
@@ -160,6 +160,29 @@ namespace FEValuesExtractors
 				    * FEValuesExtractors and in the @ref
 				    * vector_valued module.
 				    *
+				    * Note that in the current context, a
+				    * vector is meant in the sense physics
+				    * uses it: it has <code>spacedim</code>
+				    * components that behave in specific ways
+				    * under coordinate system
+				    * transformations. Examples include
+				    * velocity or displacement fields. This is
+				    * opposed to how mathematics uses the word
+				    * "vector" (and how we use this word in
+				    * other contexts in the library, for
+				    * example in the Vector class), where it
+				    * really stands for a collection of
+				    * numbers. An example of this latter use
+				    * of the word could be the set of
+				    * concentrations of chemical species in a
+				    * flame; however, these are really just a
+				    * collection of scalar variables, since
+				    * they do not change if the coordinate
+				    * system is rotated, unlike the components
+				    * of a velocity vector, and consequently,
+				    * this class should not be used for this
+				    * context.
+				    *
 				    * @ingroup feaccess vector_valued
 				    */
   struct Vector
@@ -499,11 +522,34 @@ namespace FEValuesViews
 
 				   /**
 				    * A class representing a view to a set of
-				    * <code>dim</code> components forming a
+				    * <code>spacedim</code> components forming a
 				    * vector part of a vector-valued finite
 				    * element. Views are discussed in the
 				    * @ref vector_valued module.
 				    *
+				    * Note that in the current context, a
+				    * vector is meant in the sense physics
+				    * uses it: it has <code>spacedim</code>
+				    * components that behave in specific ways
+				    * under coordinate system
+				    * transformations. Examples include
+				    * velocity or displacement fields. This is
+				    * opposed to how mathematics uses the word
+				    * "vector" (and how we use this word in
+				    * other contexts in the library, for
+				    * example in the Vector class), where it
+				    * really stands for a collection of
+				    * numbers. An example of this latter use
+				    * of the word could be the set of
+				    * concentrations of chemical species in a
+				    * flame; however, these are really just a
+				    * collection of scalar variables, since
+				    * they do not change if the coordinate
+				    * system is rotated, unlike the components
+				    * of a velocity vector, and consequently,
+				    * this class should not be used for this
+				    * context.
+				    *
 				    * @ingroup feaccess vector_valued
 				    */
   template <int dim, int spacedim=dim>