ref: 79efc5604f1df979bd1a1f5c0ee8d1d7e8bf2b61 dir: /sys/src/cmd/plot/libplot/rvec.c/
#include "mplot.h" void rvec(double xx, double yy){ e1->copyx += xx; e1->copyy += yy; vec(e1->copyx, e1->copyy); }