set view equal xy
set zzeroaxis; set xzeroaxis; set yzeroaxis
set xyplane at 0
unset border
unset key
unset xtics
unset ytics
set ztics axis

set arrow 1 from 0,0,0 to 1,0,0 head filled lw 1.5
set label 1 at 1.2,0,0 "X" center
set arrow 2 from 0,0,0 to 0,1,0 head filled lw 1.5
set label 2 at 0,1.2,0 "Y" center
set arrow 3 from 0,0,0 to 0,0,21 head filled lw 1.5
set label 3 at 0,0,23 "Z" center

set view 60, 30, 1., 1.75

set multiplot layout 1,3

set view azimuth 0.
set title 'azimuth 0' offset 0,2
splot sample [t=0:20] '+' using (cos($1)):(sin($1)):($1) with lines lw 2

set title 'azimuth 10' offset 0,2
set view azimuth 10.
replot

set title 'azimuth 60' offset 0,2
set view azimuth 60.
replot

unset multiplot

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