50 setheight 20 setxunit -2 2 setyrange -4.5 9 setxrange /I {2 0} def /r 5 def /I1 {I r 0 addv} def /I2 {I r 0 subv} def /hstep 3 def /hangle 70 def /fillstyle {hachure} def I r 2 mul .4 () cframe* xticks xsubticks xmarks 0 xtick 0 xmark .7 setlinewidth traceOx I times2 I I1 15 Arc I I2 15 Arc