Readme file for Chart::Plot 
  - Plot two dimensional data in an image. Version 0.10.

I wrote Chart::Plot to create images of some simple graphs of two
dimensional data. The other graphing interface modules to GD.pm I saw
on CPAN either could not handle negative data, or could only chart
evenly spaced horizontal data. (If you have evenly spaced or nonmetric
horizontal data and you want a bar or pie chart, you should try the
GD::Graph and Chart::* modules, available on CPAN.)

Chart::Plot will plot multiple data sets in the same graph, each with
negative or positive values in the independent or dependent
variables. Each dataset can be a scatter graph (data are represented
by graph points only) or with lines connecting successive data points,
or both. Colors and dashed lines are supported, as is scientific
notation (1.7E10). Axes are scaled and positioned automatically and
5-10 ticks are drawn and labeled on each axis.

You must have already installed the GD.pm library by Lincoln Stein,
available on CPAN or at
  http://stein.cshl.org/WWW/software/GD/
Early versions of GD (1.19 and earlier) supported only gif format; 
more recent versions support only png format. Version 1.27 also supports 
jpeg format. All these versions are still available. Chart::Plot will 
draw either gif or png by default depending on your version of GD, and 
will draw jpeg if you request and it is available.

This is a beta software and has not received exhaustive testing, but it
seems to mostly work ok. Tick labels when using scientific notation
seem to run together too often. There are a several features that it
doesn't have but should, and the code could be improved in a few
places. I will try to maintain compatibility of the public interface
if there are future versions.

Installation: unzip and untar the distribution and move into its
directory. Then the usual

  perl Makefile.PL
  make
  make test
  make install

'make test' will produce a few simple gif images, saved in files in
the current directory. I can't think of anything that could go wrong
unless you don't have GD.pm installed, but the file 'test.pl' does
offer a couple of examples. It also reports your current version of GD
and the image format(s) it supports, but this could later change if GD 
is up(down)graded.

There is also a sample cgi script, demo.cgi (which uses CGI.pm) that I
have used as a front end to Chart::Plot, but please don't write asking
me how to install a cgi script. At present time of writing, you can try 
it at http://www.pobox.com/~smorton/modules/

Sanford Morton <smorton@pobox.com>
