gawk "BEGIN{pi=3.141592654;for(t=-20;t<=20;t++){print t,9.0-1.0*sqrt(sin(1*pi*t/10)^2);}}" > _test1.txt
psxy _test1.txt -R0/360/0/10 -JP10 -Ba30g30/g1 -W2,red -P -K > fig_polar1.eps
gawk "{print $1+90, $2}" _test1.txt | psxy -R -J -B -W3,red -K -O >> fig_polar1.eps
gawk "{print $1+180,$2}" _test1.txt | psxy -R -J -B -W3,red -K -O >> fig_polar1.eps
gawk "{print $1+270,$2}" _test1.txt | psxy -R -J -B -W3,red -O >> fig_polar1.eps