ref: 7e3a4b9cfc50c4fc11ab20f5e736a8a468b6f0ad 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); }