ref: 9f2f7bc12b6d0f52a3e5bd32b5e3fdf74cdb9561 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); }