code: purgatorio

ref: eb0e026c241bd3afc6a10a6e2c7417de1b91f7e8
dir: /appl/math/doc.txt/

==========graph.b, gr.b================

I believe scientific authors and readers are best served by a
minimalist approach that makes all plots look boringly alike, except
for the data content. Here is a library that does the task of
accumulating data to find a bounding box and then draws the curves,
points, and text surrounded by readable axes.

The command   appl/math/graph.dis  is meant to be launched from wm and
then provided a file containing (x,y) pairs.  There are no options.

The library version, appl/math/gr.b, is a little more flexible.

Include gr.m and call p := GR->open().  To draw a curve, call
   p.graph(x,y)
where x and y are of real arrays. To add the string s at a point (u,v), call
   p.text(j,s,u,v)
where j is LJUST, CENTER, or RJUST to indicate whether the left, middle,
or right of the string should be at (u,v) plus one of HIGH, MED, BASE, or LOW
to indicate where the baseline of the text should be relative to (u,v).
To get text running in the y direction, add UP. To enforce the
same scaling in x and y, call   p.equalxy().

To change from the default solid line, call
   p.pen(j) where j is one
of the symbols: DASHED, DOTTED, REFERENCE, SOLID, 
CIRCLE, CROSS, or INVIS. A CIRCLE and CROSS
"pen" just puts markers at the points, and doesn't connect with line
segments. A REFERENCE line is lighter than other lines. DASHED
curve follows the curve even within one dash, and preserves arclength of
dashes and spaces. An INVIS line is sometimes handy as "strut" for
maintaining a consistent scale across a series of plots.

Finally, call
   p.out(p,"xlabel","xunit","ylabel","yunit")
to put out the curves and text in PostScript on standard output.
Axes are produced with "Guggenheim slash notation," in which the user
variable is divided by scaled units to get dimensionless numbers of
reasonable magnitude.

The function
	name := p.getfilename();
opens a dialog box to get a filename from the user and update the titlebar;
	p.bye();
pauses until the user clicks the "X" exit button in the titlebar.


<ehg@bell-labs.com> 16 May 1996