program circle_animate if( pgopen('/xwin') <= 0 ) stop call pgenv(-1.0,1.0,-1.0,1.0,1,0) call pgsfs(0) rold=0.5 x=0.0 dx=0.001 do i=1,100000 x = x + dx c x = i*dx r = 0.5 + 0.1*sin(x) call pgbbuf call pgsci(0) call pgcirc(0.0,0.0,rold) call pgsci(1) call pgcirc(0.0,0.0,r) call pgebuf rold = r end do call pgclos end