title: Gnuplot pm3d map: different x2tics, y2tics
body: <p>I can plot a "ploe figure" with:</p>
  
  <pre><code>degtorad(x)=x/180*pi
  radtodeg(x)=x/pi*180
  
  set pm3d map
  set pm3d interpolate 0,0
  set logscale zcb
  
  set palette model RGB rgbformulae 33,13,10
  
  set size ratio 1
  
  set xtics("{/Symbol b}=180{/Symbol \260}" 0)
  
  set ytics("0" -90, "10" -80, "20" -70, "30" -60, "40" -50, "50" -40, "60" -30, "70" -20, "80" -10, "90" 0, "80" 10, "70" 20, "60" 30, "50" 40, "40" 50, "30" 60, "20" 70, "10" 80, "0" 90)
  
  splot[-90:90][-90:90] 'TSC3.txt' u (radtodeg(cos(degtorad($1+90))*degtorad(90-$2))):(radtodeg(degtorad(90-$2)*sin(degtorad($1+90)))):3 notitle 
  </code></pre>
  
  <p>where column 1 contains "beta", column 2 is "alpha" but it doesn't matter.</p>
  
  <p><strong>The question is</strong></p>
  
  <ol>
  <li>how to remove the right ticmarks (<code>unset y2tics</code> doesn't work)?</li>
  <li>how to set "beta=0°" on the upper side (<code>set x2tics("{/Symbol b}=0{/Symbol \260}" 0)</code> doesn't work)?</li>
  </ol>
  
  <p><a href="https://i.stack.imgur.com/SQAkU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SQAkU.png" alt="Here is I am now"></a></p>