ref: 7f2599254a29c956ac3cdbfc28792a8290312c13
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); ellipse(screen, p, rad, rad, 0, getcolor(e1->foregr), ZP); }