set parametric
set urange [0:pi]
set vrange [0:2*pi]
set xyplane 0        # 'set ticslevel 0' is obsolute
set view equal xyz
set hidden3d
unset key 
set isosamples 24,36
set title "sphere" font "Times,20" 
set term pngcairo enh font "Times,10" size 480,480
set out "3dparam_sphere.png"
R = 3
splot R*sin(u)*cos(v), R*sin(u)*sin(v), R*cos(u)