Ideas for development in 5.3

[Ethan A M. <sf...@us...>]

The start of a new development version is an opportunity to experiment
with code that may or may not make it into a supported release.
 
What new stuff or major changes would you like to see in gnuplot?
My list of vague ideas includes

Code cleanup
------------
- remove the original axis_log/delog macros
  (not needed since introduction of generic nonlinear axis code)
- remove other obsolete macros.  HUGE? GPFAR?  MSDOS remnants?
- refactor VMS conditionals so that all the code is in vms.c
- look at using math function from libm rather than hard-coding
  them in standard.c.  For example gnuplot's implementation of
  besj0 claims accuracy to 1e-13 but the libm man page for j0
  claims accuracy to 2e-16
- matrix data should be stored as (double) not (float)
- audit all FIXMEs, surely many of them are out of date
- further optimization of STORE_WITH_LOG_AND_UPDATE_RANGE
  to increase speed and reduce code size

Build system options
--------------------
- make OSX autoconf more reliable
- offer all-qt or all-cairo build targets
- offer emscriptem build target

Terminals
---------
- canvas terminal overhaul (use browser's font support)
- dxy (support newer version of the standard)
- aquaterm (mousing!)
- svg (animation)
- latex terminals (gnuplot enhanced text => LaTeX conversion)

Fitting
-------
- Alternative algorithms (i.e. not Levenberg-Marquardt)

Core extensions
-----------------
- support 64-bit integer arithmetic for evaluation
- isosurfaces (3D contouring of 4D data)
- rethink the parallel plot implementation
- builtin equivalent to "save '|gpsavediff > outfile'"
- barycentric coordinate plots
- bubble charts 
- Q-Q plots