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TeX 1995 July
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TeX CD-ROM July 1995 (Disc 1)(Walnut Creek)(1995).ISO
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README
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1992-03-25
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This shar archive contains the following files
readme this file
congp2d3.for a preprocessor to draw contour plots on irregular
regions with gnuplot
congp2d3.dem a demo illustrating the results of congp2d3.for
ex3o.bot sample input file 1/2 for congp2d3.for
pdoge30.u3 sample input file 2/2 for congp2d3.for
poeu3o.g3 sample edited output file 1/3 from congp2d3.for
poeu3o.l3 sample edited output file 2/3 from congp2d3.for
ex3o.bdy sample edited output file 3/3 from congp2d3.for
(note: congp3d3.dem uses poeu3o.g3, poeu3o.l3, and ex3o.bdy,
so use other file names when you run congp2d3.for so that
you can see how they need to be touched up.)
I have tested congp2d3.for only under MS-DOS with the compiler
WATFOR77 or WATFOR87, but the only extension message which
the compiler produces is from the non-capital letters. Everything
else should be ANSII standard. The open statements, which vary
from OS to OS, may need to be changed.
The preprocessor congp2d3.for is a fortran program which takes
3-d data for an irregular region and finds the location of the
contour lines. Contour plots are used in several areas of
engineering to display values of a dependent variable versus
two independent ones. Sometimes the region on which
the dependent variable is defined is irregular. For instance,
the concentration of a pollutant in a lake only makes sense
within the lake, although the concentration of the pollutant
in the groundwater in the region near the lake may be another
research project. Lakes, hills, and so forth often come in
funny shapes.
I wrote congp2d3.for because a certain commercial package which
I had planned to use to put contour plots into my dissertation
dreamt up something that looked like Pike's Peak next to Death
Valley and stuck it in the middle of my plots. I wrote it in
fortran because I don't know C. Congp2d3.for reads the 3-d
data in the format which was required for the ill-fated commercial
package. It can easily be modified to read the data in the
format that gnuplot uses for 3-d data files.
As the demo says, the output from congp2d3.for may need to be
touched up in the following ways:
1. Sometimes the contour labels are less than artistically placed.
After viewing the plot with the lables where congp2d3.for
put them, the user can adjust them using a multiwindow
editor to find more suitable locations for them along
their respective contour lines. The label generated by
congp2d3 will be along the contour in question. Usually,
the user will want to edit the labels anyway to reduce the
number of significant digits and remove leading blank spaces.
2. If there is an indentation, the user may need to add a couple
of points to the file with the boundary coordinates.
3. This point is not mentioned in the demo. In the rare case
where an element has four points on a given contour, congp2d3.for
will prepare instructions to plot all 6 possible lines through
that element. The user should insert blank lines into the
file to separate points which should not be connected after all.
The program congp2d3.for uses parameter statements in the main program.
These parameter statements specify the exact correct length for all of
the arrays. The user needs to edit them to match the data in question.
The program congp2d3.for is heavily commented, to make it easier for
anyone who wishes to modify it. It is public domain, unrestricted use
software. Gnuplot itself is copyrighted but may be copied freely.
See the gnuplot documentation for details of the licensing conditions
for gnuplot.
I think that congp2d3.for could be improved by using an array of which
nodes are in each element to do the search for contour lines. Using
such an array would make it possible to contour data on completely
arbitrarily shaped regions with arbitrary node and element numbering
schemes, I think. I also think that such a change would make it
possible to recover the coordinates of all points on the boundary by
counting the number of elements that each node is in. Perhaps the
contour labeling scheme could be improved, too.
I am making congp2d3.for available without any warrantee. The email
address in the shar file will stop working as soon as I finish
my dissertation. I am starting work on April 6, 1992 but may be
accessing my accounts at UVa from time to time after that date. My
business address is as follows:
US Nuclear Regulatory Commission
Mail Stop WF6E6
Washington, DC 20555.
I will be doing a lot of travelling for this job, so letters may
take a long time to get to me.
Rose Byrne