[PATCH] Another pm3d corners2color function

[Clement L. <the...@gm...>]

Hello,

I've written up another pm3d corners2color function. It works just as
the others, i.e.,

set pm3d corners2color rms

rms4 takes the root mean square[1] of the four corners

The RMS has many physical interpretations [2]. Later on, I may write a
similar function for standard deviation...

My field of research is computational (statistical) physics. I make
heavy use of pm3d to represent three variable systems. As such, more
corners2color functions will come in useful.

The patch I've attached here was generated as advised using diff -ur
/orig/source/tree/ /my/source/tree/

Clement Law

[1] http://en.wikipedia.org/wiki/Root_mean_square
[2] http://en.wikipedia.org/wiki/Root_mean_square#Uses