From: wolf Date: Thu, 10 Dec 1998 16:03:44 +0000 (+0000) Subject: Doc update. X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=757a0372e456f4f4a5ea531e7c927401ad25d1ac;p=dealii-svn.git Doc update. git-svn-id: https://svn.dealii.org/trunk@688 0785d39b-7218-0410-832d-ea1e28bc413d --- diff --git a/deal.II/deal.II/include/numerics/data_io.h b/deal.II/deal.II/include/numerics/data_io.h index c78dc23143..22974a278c 100644 --- a/deal.II/deal.II/include/numerics/data_io.h +++ b/deal.II/deal.II/include/numerics/data_io.h @@ -223,7 +223,7 @@ class DataIn { * much easier. * * - * \subsection{GNUPLOT format} + * \subsection{GNUPLOT draft format} * * The GNUPLOT format is not able to handle data on unstructured grids * directly. Directly would mean that you only give the vertices and @@ -242,8 +242,8 @@ class DataIn { * duplicates the functionality of the #Triangulation::print_gnuplot()# * functions. These, however, offer more functionality in some respect. * The grid is represented as a sequence of lines, where each cell is - * a sequence of five vertices (the first one is appended to close the - * contour of the cell) with the data appended after each vertex. Each cell + * a sequence of five vertices (the first one is appended at the end to close + * the contour of the cell) with the data appended after each vertex. Each cell * is therefore a sequence of five lines #x y v1 v2 ...# forming together * the bounding line of this cell. After each cell, two newlines are inserted * to prevent GNUPLOT from joining the lines bounding two cells. @@ -254,6 +254,34 @@ class DataIn { * plot of the (#x-2#)th data set. For example, using #x=4# would mean to * plot the second data set. * + * This format is somewhat restricted to coninuous data and to finite elements + * of first order only. The reason for the first restriction is that it takes + * nodal values and can therefore only work if a finite element has degrees of + * freedom in the vertices of each cell. This is not the case for discontinuous + * elements. The second restriction is only a problem of quality of output: you + * actually can print quadratic or higher order elements using this style, but + * you will only seem the contour of each cell with the bounding lines of each + * cell being straight lines. You won't see the structure of the solution in the + * interior of a cell nor on the lines bounding it. + * + * + * \subsection{GNUPLOT 'quality' format} + * + * To remedy the abovementioned problems, the GNUPLOT 'quality' format was + * introduced. As noted above, GNUPLOT can handle tensor grids and displays + * them quite nicely, including hidden line removal. It can also handle more + * than one tensor grid, then called a patch. The idea now is to describe + * each cell as a patch of $N\times N$ points (in 2D). For linear elements, + * $2\times 2$ is sufficient, but for higher elements you will want to use + * a higher number. The #write_gnuplot# function writes the data in this format + * and the argument it takes is the number of subintervals it divides each cell + * into, i.e. $N-1$. + * + * This output routine also addresses the problem introduced with discontinuous + * elements, since it takes its data locally from each cell and displays it + * as a patch separately; it therefore does not use continuity and GNUPLOT will + * also plot discontinuities, if they are there. + * * * \subsection{POVRAY format} * @@ -270,7 +298,7 @@ class DataIn { * term of memory and speed to the triangle mesh supported by POVRAY. * * - * @author Wolfgang Bangerth, 1998 + * @author Wolfgang Bangerth, 1998; GNUPLOT 'quality' format by Guido Kanschat with documentation by Wolfgang Bangerth, 1998 */ template class DataOut { @@ -368,7 +396,7 @@ class DataOut { /** * Write data and grid to #out# according * to the given data format. This function - * simply calles the appropriate + * simply calls the appropriate * #write_*# function. * * In case of gnuplot output, the @@ -383,9 +411,10 @@ class DataOut { * usually has. At present the following * formats are defined: * \begin{itemize} - * \item UCD: #.inp# - * \item GNUPLOT: #.gnuplot# - * \item POVRAY: #.pov# + * \item #ucd#: #.inp# + * \item #gnuplot# and #gnuplot_draft#: + * #.gnuplot# + * \item #povray#: #.pov# * \end{itemize} * * Since this function does not need data