How do I limit a gnuplot polar to a 180 degree range?

Question

I am attempting to use gnuplot to plot the off axis response of a loudspeaker in the range +/- 90 degrees. I have this working nicely, almost entirely as a result of Creatin

Answer 1

Gnuplot gets confused if you use xrange and yrange setting which contradict the rrange setting. Thats probably why the yrange settings are ignored.

Then, you must also use set size ratio -1 in order to get the same scaling in x and yrange. When plotting only the upper two quadrants, you would get a wrong aspect ratio with set size square.

set terminal pngcairo font ',10'

set polar
set angle degrees
set size ratio 1
set lmargin 8
set style line 11 lc rgb 'gray80' lt -1
set grid polar ls 11

unset border
unset tics

set xrange [-1:1]
set yrange [0:1]
set size ratio -1

r = 1
set rtics 0.166 format '' scale 0
set label '0°' center at first 0, first r*1.05
set label '-90°' right at first -r*1.05, 0
set label '+90°' left at first r*1.05, 0

set for [i=1:5] label at first r*0.02, first r*((i/6.0) + 0.03) sprintf("%d dB", -30+(i*5))
unset raxis

set key outside top right

set output 'polar.png'
plot 'norm_polar_1000.txt' w lp ls 1 t '1k'