]> https://gitweb.dealii.org/ - dealii.git/commitdiff
Add documentation.
authorWolfgang Bangerth <bangerth@math.tamu.edu>
Mon, 21 Mar 2011 16:51:59 +0000 (16:51 +0000)
committerWolfgang Bangerth <bangerth@math.tamu.edu>
Mon, 21 Mar 2011 16:51:59 +0000 (16:51 +0000)
git-svn-id: https://svn.dealii.org/trunk@23487 0785d39b-7218-0410-832d-ea1e28bc413d

deal.II/doc/doxygen/headers/vector_valued.h

index 662bab671932e98c0a78e65ea664e8c2721e195c..9b20ff77029f73ce6e36645df713e0535f3ef865 100644 (file)
  * step-22,
  * step-31 and several other programs.
  *
+ * @note In the current context, when we talk about a vector (for example in
+ * extracting the velocity components above), we mean the word 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 FEValuesExtractors::Vector class should not
+ * be used for this case.
+ *
  *
  * @anchor VVAlternative
  * <h3>An alternative approach</h3>

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