# set terminal pngcairo  transparent enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'zeta.4.png'
set border 895 front lt black linewidth 1.000 dashtype solid
set key fixed right top vertical Right noreverse enhanced autotitle box lt black linewidth 1.000 dashtype solid
set key noinvert samplen 0 spacing 1 width 0 height 0
set key opaque
set view map scale 1
set samples 201, 201
set isosamples 201, 201
set xyplane relative 0
set cbtics  norangelimit 
set cbtics   ("-π" -3.14159, "+π" 3.14159)
set title "{/Times=16 Riemann zeta function}    {/Times:Italic=16 ζ(s) = {∑@_{/*0.5 {k=1}}^{/*.5 ∞}}  {/:Italic=12 k^{ -s}}" 
set xlabel "Real(s)" 
set xlabel  offset character -1, 0, 0 font "" textcolor lt -1 right norotate
set xrange [ -9.00000 : 9.00000 ] noreverse
set ylabel "Imag(s)" 
set yrange [ -9.00000 : 9.00000 ] noreverse
set cblabel "Phase Angle" 
set cblabel  offset character -1, 0, 0 font "" textcolor lt -1 rotate
set cbrange [ -3.14159 : 3.14159 ] noreverse
set pm3d depthorder base
set pm3d interpolate 1,1 flush begin noftriangles noborder corners2color c1
set palette positive nops_allcF maxcolors 0 gamma 1.5 color model HSV 
set palette defined ( 0 0 1 1, 1 1 1 1 )
NO_ANIMATION = 1
save_encoding = "utf8"
splot arg( zeta(x + I*y) ) with pm3d title "arg(ζ(s))"