set term png
set output "color_plot.png"
set size square

set xrange [-3:3]
set yrange [-3:3]


set palette model HSV functions gray,1,1 # HSV color space
#set palette model RGB rgbformulae 7,5,15 # traditional pm3d (black-blue-red-yellow)
#set palette model RGB rgbformulae 30,31,32 # color printable on gray (black-blue-violet-yellow-white)
#set palette model RGB functions gray,0,0 # gray: 0以上1以下の実数
set key outside
unset colorbox

max_n=4
plot n=0, min=15,\
"mod_data.txt" u ( min < $3 ? $1 : 1/0 ):($2):(0.1) notitle w circles lw 2 palette frac n/4.0,\
n=n+1, max=min, min=5,\
"" u (( min < $3 && $3 <= max ) ? $1 : 1/0 ):($2):(0.04) notitle w circles lw 2 lc palette frac n/4.0,\
n=n+1, max=min, min=-5,\
"" u (( min < $3 && $3 <= max ) ? $1 : 1/0 ):($2):(0.04) notitle w circles lw 2 palette frac n/4.0,\
n=n+1, max=min, min=-15,\
"" u (( $3 <= max ) ? $1 : 1/0 ):($2):(0.1) notitle w circles lw 2 palette frac n/4.0