[Plplot-general] Additional "plsurf3dl" pages for standard example 8

[Alan W. I. <ir...@be...>]

In my research I use the plsurf3dl function quite a lot to plot
FreeEOS results as a function of density and temperature since those
results typically are only defined for an irregular X,Y region where
the Y index limits are a function of the X index. The reason why I
have non-constant Y limits is because for certain densities the
FreeEOS calculation that models stellar conditions fails at
temperatures that are too low or temperatures that are too high, and
those failure limits do not follow a nice smooth curve.

The plsurf3dl function has long been part of the PLplot API. I
recently (just before the release) documented it in api.xml and now I
have also decided to include it in standard example 8.  For this case
(revision 13039), I have chosen indexymin and indexymax limits that
follow an ellipse (subject, of course, to index quantization errors).
I have attached the result for the -sombrero case for the fourth page
of the revised example 8 so you can get a feel for what the plotted
results look like.  The edges are definitely not smooth since that is
the nature of the beast when index limits are imposed.  However, that
is why plsurf3dl is ideal for plotting results from scientific
calculations of some model function representing the real universe
(e.g., pressure as a function of density and temperature) with two
independent variables which typically do have Y index limits which are
functions of the X index rather than constants.

Frankly, the elliptical limits look better with the -sombrero version
of the function so I am thinking of a further change to this example
such that the sombrero variant of the function is always used for the
fourth and eighth pages.  But further suggestions to make these extra
pages pleasing to the eyes would be welcome before we propagate this
change for standard example 8 to the rest of our languages.

Alan
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Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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Linux-powered Science
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