GNUPLOT: How to set reverse HOT color palette

Question

Here is the example in http://gnuplot.sourceforge.net/demo/pm3dcolors.html

set palette rgb 21,22,23; set title "hot (black-red-yellow-white)";

The above code set the hot palette. However I want a reversed hot palette, say:

white-yellow-red-black.

Small least value map to white and largest value map to black.

Answer 1

Use negative numbers to invert the palette:

set pm3d map
set palette rgb 21,22,23
splot x

gives you

whereas

set pm3d map
set palette rgb -21,-22,-23
splot x

gives you