Make Gnuplot using the mathematical minus sign

[Maurizio T. <mau...@ou...>]

Hi to everybody,

  Yesterday I posted a question on StackOverflow about the possibility to
use the mathematical minus sign for negative numbers for tick labels in
Gnuplot instead of the hyphen. (This is a request I got from the referee of
a paper I've just submitted.)

Although I have never hacked Gnuplot, I am fluent with C/C++ and would like
to try to write a patch that implements this feature. I would like to ask
you which would be the best way to do this:

1. Implement a pair of commands ("set hyphenminus" / "unset hyphenminus") 
which change this setting globally, i.e., on the X/Y/X2/Y2 axes.

2. Implement a new formatting sequence, like "%h", which takes care of using
the correct character.

My preference goes to the first option (if one cares for typographical
correctness, chances are that it wants it on every axis.). Moreover, I would
like to make the mathematical minus the default, and leave the possibility
to use the hyphen only as a way to retain backwards compatibility (this is
what Matplotlib does).

What do you think? Do you have suggestions about how to properly code this?

  Maurizio.