[Gnuplot-info] is painting with corners2color working incorrectly for Y axis?

[Yury <yur...@gm...>]

Hi,

Can't test with other versions right now, but 
with 5.4.3 and 6.0.0 on linux I'm having an 
issue plotting this:

set terminal x11 ;
set size square
set xrange [-3:3]; set yrange [-3:3];
set samples 7
sigma = 2.0;
f(x,y) = (1/(2*pi*sigma**2)) * 
exp(-(x**2+y**2)/(2*sigma**2)) ;
set grid
set pm3d map corners2color c1;
splot \
   f(x,y) \

AFAIU, this should construct radial-symmetric 
color map with grid lines separating color changes.

What it makes instead on my system is a colormap 
with an arbitrary number of samples for Y axis. 
I see at least 8 color changes along Y axis, and 
generally color rectangles are smaller along Y 
axis, while grid squares are okay.

Is this a known or documented behaviour?

-Yury