Changeset 3119

Timestamp:

Jun 8, 2006, 2:53:26 PM (18 years ago)

Author:

howard

Message:

Modified the description of symbolic tags in 3.1.7

File:

• documentation/user_manual/anuga_user_manual.tex (modified) (5 diffs)

documentation/user_manual/anuga_user_manual.tex

@@ -310 +310 @@
    \item a dictionary \code{boundary} that stores the edges on
    the boundary and associates each with one of the symbolic tags \code{`left'}, \code{`right'},
-   \code{`top'} or \code{`bottom'}.
+   \code{`top'} or \code{`bottom'}. (For more details on symbolic tags,
+   see page \pageref{ref:tagdescription}.)
 
 \end{itemize}
@@ -494 +495 @@
 \end{itemize}
 
-Before describing how these boundary conditions are assigned, we
-recall that the definition of a mesh uses a variable \code{boundary}
-to store the edges of the mesh that lie on the boundary. (In the
-code we are discussing, \code{boundary} was one of the three
-variables returned by the function \code{rectangular}.)
-
-This variable \code{boundary} is a Python dictionary and it serves
-not only to hold the edges that make up the boundary but also to
-assign symbolic tags to these edges to distinguish different parts
-of the boundary. In this example, the tags  used are \code{`left',
-\code{`right'}, \code{`top'} and \code{`bottom'}, corresponding to
-the left, right, top and bottom of the rectangle bounding the mesh,
-and the function \code{rectangular} automatically assigns these tags
-to the boundary edges when it generates the mesh. The tags are used
-as keys for the dictionary, so that, for example,
-\code{boundary[`left']} is a list of the mesh edges that lie along
-the left part of the boundary.
+\label{ref:tagdescription}Before describing how these boundary
+conditions are assigned, we recall that a mesh is specified using
+three variables \code{points}, \code{vertices} and \code{boundary}.
+In the code we are discussing, these three variables are returned by
+the function \code{rectangular}; however, the example given in
+Section \ref{sec:realdataexample} illustrates another way of
+assigning the values, by means of the function
+\code{create\_mesh\_from\_regions}.
+
+These variables store the data determining the mesh as follows. (You
+may find that the example given in Section \ref{sec:meshexample}
+helps to clarify the following discussion, even though that example
+is a \emph{non-rectangular} mesh.)
+
+\begin{itemize}
+\item The variable \code{points} stores a list of 2-tuples giving the
+coordinates of the mesh points.
+
+\item The variable \code{vertices} stores a list of 3-tuples of
+numbers, representing vertices of triangles in the mesh. In this
+list, the triangle whose vertices are \code{points[i]},
+\code{points[j]}, \code{points[k]} is represented by the 3-tuple
+\code{(i, j, k)}.
+
+\item The variable \code{boundary} is a Python dictionary that
+not only stores the edges that make up the boundary but also assigns
+symbolic tags to these edges to distinguish different parts of the
+boundary. An edge with endpoints \code{points[i]} and
+\code{points[j]} is represented by the 2-tuple \code{(i, j)}. The
+keys for the dictionary are the 2-tuples \code{[i, j]} corresponding
+to boundary edges in the mesh, and the values are the tags are used
+to label them. In the present example, the value \code{boundary[i,
+j]} assigned to \code{[i, j]} is one of the four tags \code{`left'},
+\code{`right'}, \code{`top'} or \code{`bottom'}, depending on
+whether the boundary edge represented by \code{(i, j)} occurs at the
+left, right, top or bottom of the rectangle bounding the mesh. The
+function \code{rectangular} automatically assigns these tags to the
+boundary edges when it generates the mesh.
+\end{itemize}
 
 The tags provide the means to assign different boundary conditions
 to an edge depending on which part of the boundary it belongs to.
-(Later we shall describe an example that uses different boundary
-tags---we are not limited to using `left', `right', `top' and
-`bottom'.)
+(In Section \ref{sec:realdataexample} we describe an example that
+uses different boundary tags---in general, the possible tags are not
+limited to `left', `right', `top' and `bottom', but can be selected
+by the user.)
 
 Using the boundary objects described above, we assign a boundary
@@ -564 +588 @@
 See Section \ref{sec:file formats} (page \pageref{sec:file formats})
 for more on NetCDF and other file formats.
+
+The following is a listing of the screen output seen by the user
+when this example is run:
+
+\verbatiminput{examples/runupoutput.txt}
 
 
@@ -2645 +2674 @@
 
 \subsubsection{How do I tag interior polygons?}
-At the moment create_mesh_from_regions does not allow interior polygons 
-with symbolict tags. If tags are needed, the interior polygons must be
-created subsequently. For example, given a filename of polygons representing
-solid walls (in Arc Ungenerate format) can be tagged as such using the code 
-snippet:
-\begin{verbatim} 
+At the moment create_mesh_from_regions does not allow interior
+polygons with symbolic tags. If tags are needed, the interior
+polygons must be created subsequently. For example, given a filename
+of polygons representing solid walls (in Arc Ungenerate format) can
+be tagged as such using the code snippet:
+\begin{verbatim}
   # Create mesh outline with tags
   mesh = create_mesh_from_regions(bounding_polygon,
@@ -2659 +2688 @@
 
   # Generate and write mesh to file
-  mesh.generate_mesh(maximum_triangle_area=max_area)                  
+  mesh.generate_mesh(maximum_triangle_area=max_area)
   mesh.export_mesh_file(mesh_filename)
-\end{verbatim} 
+\end{verbatim}
 
 Note that a mesh object is returned from \code{create_mesh_from_regions}