ref: c2a5d7e3f28e86aeef1e4e37e2b88e46af90b62c
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); }