ref: 2c9f4c21ad0b5e66f06a3613f6e21d5fe9f0da6a 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); }