ref: 1e8a9ebb0f76b0ebe8eb31d79c44324c1c1ed70f 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); }