圈 Describing a Circle; 1305 Edmund Conf. 232 in Early Eng. Poems & Lives Saints (1862) 77 Þreo rounde cerclen heo wrot: in þe paume amidde., concentric; 1400 G. Chaucer Treat. Astrolabe (Cambr. Dd.3.53) (1872) i. §17. 10 The heued of capricorne turnyth euermo consentryk vp-on the same cercle.
x = sin( -5.009757041932 * y ) – cos( 5.0073237419122 * x );
y = sin( -5.006352424622 * x ) – cos( 5.0065770149236 * y );