Reference documentation for deal.II version Git aa2075a 2017-04-21 00:33:12 +0200
|Vector (const unsigned int first_vector_component)|
Extractor for a vector of
spacedim components of a vector- valued element. The value of
spacedim is defined by the FEValues object the extractor is applied to. The result of applying an object of this type to an FEValues, FEFaceValues or FESubfaceValues object is of type FEValuesViews::Vector.
Note that in the current context, a vector is meant in the sense physics uses it: it has
spacedim 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.
Default constructor. Initialize the object with an invalid component. This leads to an object that can not be used, but it allows objects of this kind to be put into arrays that require a default constructor upon resizing the array, and then later assigning a suitable object to each element of the array.
|unsigned int FEValuesExtractors::Vector::first_vector_component|