如何在gnuplot中为正值和负值设置colorbox

Question

I would like to set palette rgbformulae in such way that, the colors will be distributed in positive and negative values equally. I want to go from blue (negative values) to 0 (white), to red (positive values). I can't able to change the rgbformulae for that.

 set cbrange [-5:5]
 set palette maxcolors 10
 set palette rgbformulae ? ? ?

Answer 1

There is the set palette defined (zrgb, ...) command which can be used to explicitly set colors (rgb) at specific z-values. Gnuplot will interpolate the colors in between.

I skipped the set palette maxcolors 10 , but the following might be a starting point:

set xrange [-1:1]
set yrange [-1:1]
set zrange [-5:5]

set pm3d map
set cbrange [-5:5]
set palette defined (-5 0 0 1, 0 1 1 1, 5 1 0 0)

set terminal png
set output 'colors.png'
splot 5*x

I'm using Gnuplot 4.6.6 on Debian Jessie.