ref: 0fd8a9a13db2c006b4b5f3ab5c6a4532a1fb1d3b 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); }