ref: 14cfa56253beb8a2ad8e4700c8c26a6ff6d16ee7
dir: /sys/src/cmd/plot/libplot/circ.c/
#include "mplot.h" void circ(double xc, double yc, double r){ Point p; int rad; p.x=SCX(xc); p.y=SCY(yc); if (r < 0) rad=SCR(-r); else rad=SCR(r); m_circ(p, rad, e1->foregr); }