ref: 5f7a6b7ea3c4ae1b51beffe3309e9b6b0491e71f 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); }