`Gre' (rhymes with `flee') is an extensible plotting language designed
by a scientist, for scientists.  It can draw x-y plots, contour plots,
and image plots.  The `gre' homepage is on the web, at

    https://github.com/dankelley/gre

Gre has not been updated in over a decade, as the author (Dan Kelley) started
using R for both data processing and plotting, many years ago.

For what it's worth (and that is not much, given a decade of no action) the
following is an old to-do list for this project.

* add 'set colorname' and 'read colorname'

* is there an error on fonts of contour labels on multipage?
 
* -0 on axes sometimes

* DOCUMENT THE following, perl-like, thing:
 
	@t=(1,2,3);
	print $t[0], "\n";
	print $t[1], "\n";
	print $t[2], "\n";

* accented fonts

* ERROR: 'set x type log' won't parse
            set x type log;

* fix 'skip', then document ... it's way broken...
      open "test.dat" or die;
      skip;
      read columns x=1 y=2;
      print columns;

* if opening a pipe, and something dies, return bad value

* only state the fonts that are actually used.

* set arrow size as 10 percent of length;  BROKEN??

* doc: rework 'grammar', putting user subs at toplevel, also 'cmd' (where the heck IS cmd??)

* COMPLETE+DOCUMETN 'tagged_value' 
	** make it actually scan the line, etc
	** maybe also make it accept just 1 argument?

   testpgm: print tagged_value("x=", "x= 10 y=20"), "\n";

subs.cpp:88 in tagged_value(x=,x:10 y=20)
1

* fix bug noted in manual at 'print variables' ('my' variables)

* allow split(argument), needed for:

   sub get_tagged_value($$) {
       my $tag = $_[0];
       my $source = $_[1];
       print "tag ", $tag, "\n";
       print "input line '", $_, "'\n";
       @source = split($source);
       for ($i = 0; $i < $#source; $i++) {
	   print "'", $source[$i], "'\n";
	   print "'", $tag, "' ... '", $source[$i], "' match? ", ($tag eq $source[$i]), "\n";
	   print "got ",  $source[$i + 1], "\n" if ($tag eq $source[$i]);
	   if ($tag eq $source[$i]) {
	       print "before returning ", $source[$i + 1], "\n";
	       return $source[$i + 1];
	   }
       }
       return 0;
   }
   open(IN,"test.dat") or die;
   $keep = <IN>;
   print;
   $x = get_tagged_value("x=", $keep);
   print "x is", $x, "\n";


* Bessel's fcns (in a package, if perl does it that way)

* add $_wd (alter if do 'cd' ... if I have that)

* figure out where to put gre-mode.el, and change 
	Makefile.in
	*spec
to point to the right place

* perhaps make it 'set text|line|fill color' ?

* doc/'draw image' -- say more; give example.

* 'set image colorscale' image not same as contours more rounded

test.gre:
    set x grid 0 1 0.25;
    set y grid 1 2 0.25;
    open(IN, "test.dat") or die;
    read grid data IN;
    print grid;
    convert grid to image size 512 512;
    print image;
    #set image colorscale hsv .33 0 1 1 hsv .33 1 1 3 increment 0.5;
    set image colorscale rgb 1 0 0 1.0 rgb 0 1 0 3.0 increment 0.5;
    draw image;
    draw contour;

test.dat:
    0 0 0 0 0
    0 1 2 1 0
    0 2 3 2 0
    0 1 2 1 0
    0 0 0 0 0

* err() gives wrong linenumbers (parser.y:4367) -- gives last line of file

* 'set image grayscale'
* 'draw image palette'

* i18n: trying with gre_main first.  Not sure how to handle files,
though.

* errors in spacing after math (line 3 from bottom)

     $y = 3.0; $dy = 1.2;
     set font size 40;
     draw label "fff"          at 3 $y cm; $y += $dy;
     draw label "f0f"          at 3 $y cm; $y += $dy;
     draw label "f\(0\)f"      at 3 $y cm; $y += $dy;
     draw label "f\(f0\)f"     at 3 $y cm; $y += $dy;
     draw label "f\(\alpha\)f" at 3 $y cm; $y += $dy;
     draw label "f\(f\)f"      at 3 $y cm; $y += $dy;
     draw label "f\(3*(f)\)f"  at 3 $y cm; $y += $dy;

 what it should be is:
	if in_math && last_was_roman
		thinspace
	if leaving_math && last_was_roman
		thinspace
 where last_was_roman is set for any non-greek,non-punct,non-numeric character
 in mathmode.

 search for grstring.cpp ... 'thinspace'


* popt seems broken.  Doesn't recognize the options.

* Change: -e ... style should still do the cmdfile, but doesn't

* problem with some 'cm' commands (e.g. draw line from) if no axes yet

* make 'GriPath' be based on STL vector<pair<pair<double,double>,bool>>?

1. Package support
==================

* parse 'package NAMESPACE' 98-nov-08

TO DO:

* treat following as special (belongs to main) -- parser.y:2809
	ARGV
	_
	_...  (any variable starting with underscore, e.g. $_xleft)

* search for '::' in name, and don't prepend if so -- parser.y:2809

* same for '@@' type variables

* add seawater.gre to /opt... fix Makefile, spec files.

* add package for interpolation, e.g.
	read columns x y;
	interpolate to x 0 1 10;
  to interpolate to x being 0,1,2,..., 10??